EX-4.2




 Exhibit 4.2 

AON CORPORATION 
 AON
GLOBAL HOLDINGS PLC 
  
  

SECOND INDENTURE SUPPLEMENT 

DATED AS OF DECEMBER 2, 2021 

TO 
 THE AMENDED AND
RESTATED INDENTURE 
 DATED AS OF APRIL 1, 2020 

 
  

THE BANK OF NEW YORK MELLON TRUST COMPANY, N.A. 

TRUSTEE 
  

 
 DEBT
SECURITIES 











 THIS SECOND INDENTURE SUPPLEMENT (the “Second Indenture Supplement”), is
dated as of December 2, 2021, among Aon Corporation, a corporation duly organized and existing under the laws of the State of Delaware (hereinafter sometimes called the “Company” , which term includes any successor Person under
the Indenture hereinafter referred to), Aon Global Holdings plc, a public limited company duly organized and existing under the laws of England and Wales (hereinafter sometimes called “AGH” or the “Co-Issuer”, which term includes any successor Person under the Indenture hereinafter referred to, and, together with the Company, the “Issuers”), Aon plc, a public limited company duly
organized and existing under the laws of Ireland (hereinafter sometimes called “Aon Ireland”), Aon Global Limited, a private limited company duly organized and existing under the laws of England and Wales and prior to its re-registration, a public limited company formed under the laws of England and Wales named Aon plc (hereinafter sometimes called the “Aon UK” and, together with Aon Ireland, the
“Guarantors” and each, a “Guarantor”), and The Bank of New York Mellon Trust Company, N.A., a national banking association duly incorporated and existing under the laws of the United States of America (hereinafter
sometimes called the “Trustee”, which term shall include any successor trustee appointed pursuant to Article Seven of the Base Indenture), and is a supplemental indenture amending and restating the Base Indenture (as defined below).

 WITNESSETH: 

WHEREAS, the Company, AGH, the Guarantors and the Trustee executed and delivered an Amended and Restated Indenture, dated as of April 1,
2020 (the “Base Indenture” and together with this Second Indenture Supplement, the “Indenture”), to provide for the issuance from time to time for its lawful purposes debt securities (hereinafter called
“Securities” or, in the singular, “Security”) evidencing its unsecured indebtedness. 
 WHEREAS,
Section 10.01 of the Base Indenture provides that a supplemental indenture may be entered into by the Company, AGH, Aon Ireland and Aon UK when authorized by or pursuant to a Board Resolution, and the Trustee without the consent of any Holders
to make provisions to establish the form or terms of Securities of any series as permitted by Sections 2.01 and 2.03 of the Base Indenture. 

WHEREAS, solely with respect to the application of such provisions to the Offered Securities, the Company, the
Co-Issuer and the Guarantors, desire to (i) effect that the Issuers co-issue the Notes, (ii) effect such guarantee by Aon Ireland and Aon UK,
(iii) establish the form and terms of the Notes without the consent of any Holders as permitted by Sections 2.01 and 2.03 of the Base Indenture and (iv) execute a supplemental indenture to the Base Indenture pursuant to Section 10.01
thereof by amending and restating herein the Base Indenture in relevant part. 
 WHEREAS, each of the Company, the Co-Issuer, Aon Ireland and Aon UK represents that all acts and things necessary to present a valid and binding supplemental indenture and agreement according to its terms have been done and performed, and the
execution of this Indenture as a supplemental indenture to the Base Indenture by each of the Company, the Co-Issuer, Aon Ireland and Aon UK has in all respects been duly authorized, and each of the Company,
the Co-Issuer, Aon Ireland and Aon UK, in the exercise of legal rights and power in it vested, is executing this Indenture. 

NOW, THEREFORE, for and in consideration of the foregoing premises, the Issuers, the Guarantors and the Trustee mutually covenant and agree
for the equal and proportionate benefit of the respective Holders from time to time of the Notes as follows: 











 ARTICLE I 

DEFINED TERMS 
 SECTION 1.01.
Defined Terms. Except as otherwise expressly provided in this Second Indenture Supplement or in the respective forms of Note attached as Exhibit A hereto or otherwise clearly required by the context hereof or thereof, all capitalized
terms used and not defined in this Second Indenture Supplement that are defined in the Base Indenture shall have the meanings assigned to them in the Base Indenture. For all purposes of this Second Indenture Supplement only: 

“Base Indenture” has the meaning set forth in the recitals hereof. 

“Board of Directors”, with respect to the Issuers, shall mean the board of directors (or comparable governing body) of each
such Issuer, the executive committee of each such Issuer or any other committee duly authorized to exercise the powers and authority of the board of directors (or comparable governing body) of each such Issuer with respect to this Indenture. 

“Closing Date” means December 2, 2021. 

“Co-Issuer” means the Person named as the
“Co-Issuer” set forth in the preamble hereof, until a successor Person shall have become such pursuant to the applicable provisions of this Indenture, and thereafter
“Co-Issuer” shall mean such successor Person. 
 “Company” (i) with
respect to the provisions set out in the Second Indenture Supplement, has the meaning set forth in the preamble hereof, until a successor Person shall have become such pursuant to the applicable provisions of the Indenture, and thereafter
“Company” shall mean such successor Person and (ii) with respect to the Base Indenture and only in the context where the Second Indenture Supplement has not expressly amended and restated a provision of the Base Indenture, the term
“Company” shall mean (a) the Person named as the “Company” in the first paragraph of the Base Indenture until a successor Person shall have become such pursuant to the applicable provisions of this Indenture, and thereafter
“Company” shall mean such successor Person and (b) the Person named as the “AGH” in the first paragraph of the Base Indenture, acting in its capacity as a co-issuer in accordance with
this Second Indenture Supplement, until a successor Person shall have become such pursuant to the applicable provisions of this Indenture, and thereafter “Company” shall include such successor Person. 

“Comparable Treasury Issue” means with respect to the Notes to be redeemed, the U.S. Treasury security selected by the
Quotation Agent as having a maturity comparable to the remaining term of such Notes to be redeemed (assuming the Notes matured on the Par Call Date) that would be utilized, at the time of selection and in accordance with customary financial
practice, in pricing new issues of corporate debt securities of comparable maturity to the remaining term of such Notes (assuming the Notes matured on the Par Call Date). 

“Comparable Treasury Price” means, with respect to any redemption date, (i) the average of three Reference Treasury
Dealer Quotations for such redemption date, after excluding the highest and lowest such Reference Treasury Dealer Quotations, or (ii) if the Quotation Agent is given fewer than five such Reference Treasury Dealer Quotations, the average of all
such quotations, or (iii) if only one Reference Treasury Dealer Quotation is received, such quotation. 
 “Global Securities
Legend” means the legend set forth on the form of Note attached as Exhibit A hereto. 

  
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 “Guarantors” has the meaning set forth in the recitals hereof. 

“Indenture” has the meaning set forth in the recitals hereof. 

“Interest Payment Date” has the meaning set forth in Section 2.02 hereof. 

“Notes” means a new series of Securities to be co-issued by the Company and the Co-Issuer to be known as $500,000,000 aggregate principal amount of 2.600% senior notes due 2031 (the “Notes,” substantially in the form attached hereto as Exhibit A), fully and
unconditionally guaranteed as to payment of principal and interest by Aon Ireland and Aon UK, each series designated in Section 2.01 hereof that are authenticated and delivered under the Indenture. For all purposes of this Second Indenture
Supplement, the term “Notes” shall include the Notes initially issued on the Closing Date and any other Notes of each such series issued after the Closing Date. For purposes of the Indenture, the Notes shall constitute a single series of
Securities under the Indenture and shall vote together to the extent so provided in the Indenture. 
 “Original Indenture”
has the meaning set forth in the recitals hereof. 
 “Par Call Date” means September 2, 2031 (the date that is three
months prior to the stated maturity date for the Notes). 
 “Quotation Agent” means the Reference Treasury Dealer appointed
by the Issuers. 
 “Reference Treasury Dealer” means each of J.P. Morgan Securities LLC, BofA Securities, Inc. and Goldman
Sachs & Co. LLC (or their respective affiliates that are primary U.S. government securities dealers in New York City, each of which is referred to as a “Primary Treasury Dealer”) and their respective successors and two other
nationally recognized investment banking firms that are Primary Treasury Dealers appointed from time to time by us; provided, however, that if any of the foregoing shall cease to be a Primary Treasury Dealer, we will substitute therefor another
Primary Treasury Dealer. 
 “Reference Treasury Dealer Quotations” means, with respect to each Reference Treasury Dealer
and any redemption date, the average, as determined by the Quotation Agent, of the bid and asked prices for the Comparable Treasury Issue (expressed in each case as a percentage of its principal amount) quoted in writing to the Quotation Agent by
such Reference Treasury Dealer at 5:00 p.m., New York City time, on the third business day preceding such redemption date. 

“Regular Record Date” has the meaning set forth in Section 2.02 hereof. 

“Treasury Rate” means, with respect to any redemption date, the rate per annum equal to the semi-annual equivalent yield to
maturity of the Comparable Treasury Issue, assuming a price for the Comparable Treasury Issue (expressed as a percentage of its principal amount) equal to the Comparable Treasury Price for such redemption date. 

“Trustee” has the meaning set forth in the preamble hereof. 

The parties hereto acknowledge that certain terms are defined in both the Base Indenture and in this Second Indenture Supplement. The parties hereto hereby
agree that, unless otherwise expressly stated or the context otherwise requires, any term which is defined in either the Base Indenture or this Second Indenture Supplement, when used with respect to or in the respective certificates evidencing the
Notes, shall have the meaning set forth in this Second Indenture Supplement. 

  
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 ARTICLE II 

TERMS OF THE NOTES 
 SECTION
2.01. Establishment of the Notes. 
 (a) There is hereby authorized and established a series of Securities designated the 2.600%
senior notes due 2031, limited in aggregate principal amount to $500,000,000 (except for Notes authenticated and delivered upon registration of transfer of, or in exchange for, or in lieu of, other Notes pursuant to Sections 2.05, 2.06, 2.07, 3.03,
6.01 or 10.04 of the Indenture); provided that the Issuers may, from time to time, without notice to or consent of Holders or beneficial owners of the Outstanding Notes, create and issue additional notes of this series of Securities so as to
increase the aggregate principal amount of Notes Outstanding in compliance with the procedures set forth in the Indenture, including Sections 2.03 and 2.04 thereof, by issuing additional Securities having the same ranking, interest rate, maturity
and other terms (except for the issue date, public offering price and, in some cases, the first Interest Payment Date and the date from which interest shall begin to accrue) as the Notes then Outstanding; provided, further, that any such additional
Securities will constitute part of the same series as the Notes issued on the Closing Date; and provided, further, that if the Issuers issue such additional Securities that are not fungible for U.S. federal income tax purposes with the Notes issued
on the Closing Date, the additional Securities will have a separate CUSIP number. 
 (b) The form and terms of the Notes have been
established pursuant to authority duly granted by the Board Resolutions of the Company, adopted on November 25, 2021 (the “Company Board Resolutions”), and the Board Resolutions of AGH, adopted on November 25, 2021 (together, the
“Co-Issuer Board Resolutions” and together, the “Board Resolutions”), in accordance with Section 2.03 of the Indenture, and the Corporate Secretary of the Company has
certified that the Board Resolutions have been duly adopted by the Board of Directors of the Company and are in full force and effect on the date of such certification and the Corporate Secretary of the
Co-Issuer has certified that the Board Resolutions have been duly adopted by the Board of Directors of the Co-Issuer and are in full force and effect on the date of such
certification. 
 SECTION 2.02. Terms of the Notes. The following terms relate to the Notes: 

(a) The Notes hereby established are a series of Securities having the title “2.600% senior notes due 2031 with full and unconditional
guarantees as to payment of principal and interest by Aon plc and Aon Global Limited” in and pursuant to authority duly granted by the Board Resolutions the terms and provisions of the Notes as provided for in Section 2.01 of the Indenture
with the further terms and provisions as set forth in the form of the Notes attached hereto as Exhibit A. 
 (b) The initial aggregate
principal amount of the Notes that may be issued, authenticated and delivered under the Indenture (except for Notes authenticated and delivered upon registration of, transfer of, or in exchange for, or in lieu of, other Notes or Notes authenticated
and delivered as Additional Securities pursuant to Section 2.01 of the Base Indenture) is $500,000,000. 
 (c) The Stated Maturity on
which the principal of the Notes shall be due and payable (unless earlier redeemed) shall be December 2, 2031. 
 (d) The principal of
the Notes shall bear interest at the rate of 2.600% per annum, which interest shall accrue from the most recent Interest Payment Date with respect to the Notes to which interest has been paid or duly provided for, and if no interest has been paid or
duly provided for, from and 

  
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including December 2, 2021, payable semi-annually in arrears on June 2 and December 2 (each, an “Interest Payment Date”) in each year, commencing June 2,
2031, to the Persons in whose names the Notes are registered at the close of business on the May 17 or November 17 immediately preceding such Interest Payment Dates (each, a “Regular Record Date”) regardless of whether
such Regular Record Date is a Business Day. 
 (e) Interest on the Notes shall be calculated on the basis of a
360-day year of twelve 30-day months. 
 (f) At any time and
from time to time prior to a Par Call Date, the Issuers may at their option redeem all or some of the Notes at a redemption price equal to the greater of: 

(i) 100% of the principal amount of the Notes being redeemed; and 

(ii) the sum of the present values of the remaining scheduled payments of principal and interest on the Notes being redeemed (not including any
portion of such payments of interest accrued as of the redemption date) from the redemption date to the Par Call Date, discounted to the date of redemption on a semi-annual basis (assuming a 360-day year
consisting of twelve 30-day months) at the Treasury Rate (as defined below), plus 20 basis points (0.200%), 
 plus
accrued and unpaid interest on the principal amount of the Notes being redeemed to but excluding the redemption date. 
 (g) At any time and
from time to time on or after the Par Call Date, the Issuers may at their option redeem all or some of the Notes at a redemption price equal to 100% of the principal amount of the Notes to be redeemed, plus accrued and unpaid interest on the
principal amount of the Notes being redeemed to but excluding the redemption date. 
 Notwithstanding the foregoing, installments of
interest on Notes being redeemed that are due and payable on interest payment dates falling on or prior to a redemption date will be payable on the interest payment date to the registered holders as of the close of business on the relevant record
date according to such Notes and the indenture. 
 (h) All payments of interest and principal, including payments made upon any
redemption or repurchase of the Notes, will be payable in U.S. Dollars. 
 (i) The Notes are designated, pursuant to Section 2.01 of the
Indenture, as being entitled to the benefits of the Guarantees of Aon Ireland and Aon UK, and Article Fifteen of the Base Indenture shall apply, and inure to the benefit of, the Notes. 

(j) The Notes are subject to redemption at the option of the Issuers as provided in the form of Note attached hereto as
Exhibit A and in the Indenture. 
 (k) The Notes shall have such other terms and provisions as are set forth in the
form of Note attached hereto as Exhibit A (all of which are incorporated by reference in and made a part of this Second Indenture Supplement as if set forth in full at this place). 

SECTION 2.03. Denominations. The Notes shall be issued in registered form without interest coupons and only in minimum denominations of
$2,000 and integral multiples of $1,000 in excess thereof. 

  
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 SECTION 2.04. Form. The Notes will be represented by one or more Global Securities.
The Notes shall be in substantially the form set forth in Exhibit A hereto with such changes therein as may be authorized by any officer of the Company and the Co-Issuer executing
such Notes by manual or facsimile signature, such approval to be conclusively evidenced by the execution thereof by such applicable officer. 

The terms and provisions contained in the Notes shall constitute, and are hereby expressly made, a part of this Second Indenture Supplement,
and the Company, the Co-Issuer and the Trustee, by their execution and delivery of this Second Indenture Supplement, expressly agree to such terms and provisions and to be bound thereby. However, to the extent
any provision of any Note conflicts with the express provisions of this Second Indenture Supplement, the provisions of this Second Indenture Supplement shall govern and be controlling. 

The Notes shall be issued as registered Securities without coupons. 

ARTICLE III 
 AMENDMENTS TO
INDENTURE FOR THE BENEFIT 
 OF HOLDERS OF THE NOTES 

SECTION 3.01. Amendment to Section 4.01—Payment of Principal, Premium and Interest. Section 4.01 of the
Base Indenture is deleted in its entirety and is hereby replaced and superseded with the following provision: 

“Section 4.01. Payment of Principal, Premium and Interest. The Issuers will
duly and punctually pay or cause to be paid the principal of and premium, if any, and interest, if any, on each series of Notes, at the place, at the respective times and in the manner provided in the terms of the applicable series of Notes and in
this Indenture. The interest on the applicable series of Notes shall be payable only to or upon the written order of the Holders thereof and at the option of the Issuers may be paid by wire transfer, other electronic means or mailing checks for
such interest payable to or upon the order of such Holders at their last addresses as they appear on the Security Register for such Notes. 

SECTION 3.02. Amendment to Section 4.02—Offices for Notices and Payments, etc. Section 4.02 of the Base
Indenture each reference to “the Company” is deleted and is hereby replaced with “the Issuers”. 
 SECTION 3.03.
Amendment to Section 4.03—Provisions as to Paying Agent. In Section 4.03 of the Base Indenture each reference to “the Company” is deleted and is hereby replaced with “the Issuers”; provided
that Section 4.03(b) is deleted in its entirety and is hereby replaced and superseded with the following provision: 

“(b) If either the Company or the Co-Issuer shall act as its own paying agent, it
will, on or before each due date of the principal of and premium, if any, and interest, if any, on the Securities of any series set aside, segregate and hold in trust for the benefit of the Holders of the Securities of such series entitled thereto a
sum sufficient to pay such principal, premium, or interest so becoming due. The applicable Issuer will promptly notify the Trustee of any failure to take such action.” 

  
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 SECTION 3.04. Amendment to Section 4.04—Statement by Officers as
to Default. Section 4.04 of the Base Indenture shall be deleted in its entirety and is hereby replaced and superseded with the following provision: 

“Section 4.04. Statement by Officers as to Default. 

(a) Either the Company or the Co-Issuer will deliver to the Trustee, on or before
a date not more than four months after the end of each fiscal year of the Company or the Co-Issuer, as applicable, ending after the date hereof, an Officers’ Certificate of the Company or the Co-Issuer, as applicable, which shall include the statements provided for in Section 16.04 and stating whether or not to the best knowledge of the signers thereof either the Company or the Co-Issuer is in default in the performance or observance of any of the terms, provisions and conditions of this Indenture to be performed or observed by it and specifying all such defaults and the nature thereof of
which it may have knowledge. 
 (b) The Company and the Co-Issuer, as
applicable, will deliver to the Trustee, as soon as practicable upon becoming aware of any default (which word has the meaning of the word “default” as used in Section 6.07) or Event of Default with respect to a particular series of
Securities that has occurred and is continuing, a written notice setting forth the details of such default or Event of Default.” 

SECTION 3.05. Amendment to Section 4.05—Payment of Additional Amounts. Section 405 of the Base Indenture
is deleted in its entirety and is hereby replaced and superseded with the following provision: 

“Section 4.05. Payment of Additional Amounts. 

(a) All payments made by any Guarantor (including any successor in interest to any of the foregoing) in respect of its
Guarantee shall be made free and clear of and without withholding or deduction for or on account of any present or future income, stamp or other tax, duty, levy, impost, assessment or other governmental charge of any nature whatsoever imposed or
levied by or on behalf of the government of the United Kingdom or Ireland, as applicable, or, in each case, by any authority or agency therein or thereof having the power to tax (collectively, “Taxes”), unless such Guarantor is
required to withhold or deduct Taxes by law. 
 If a Guarantor is required to withhold or deduct any amount for or on
account of Taxes from any payment made with respect to its Guarantee, such Guarantor shall pay such additional amounts (the “Additional Amounts”) as may be necessary in order that the net amounts received in respect of such payments
by the beneficial owner, the Trustee or any Agent, as the case may be, after such withholding or deduction (including any such deduction or withholding from such Additional Amounts), shall not be less than the amounts that would have been received
in respect of such payments on the Guarantees in the absence of such withholding or deduction; provided however that no such Additional Amounts will be payable with respect to Taxes: 

  
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 (1) that would not have been so imposed or levied but for the existence of any present or
former connection between the relevant Holder or beneficial owner of the Notes (or between a fiduciary, settlor, beneficiary, member or shareholder of, or possessor of a power over, such Holder or beneficial owner, if such Holder or beneficial owner
is an estate, trust, partnership or corporation), and the United Kingdom or Ireland, as applicable, or, in each case, any political subdivision or territory or possession thereof or therein or area subject to its jurisdiction, including, without
limitation, such Holder or beneficial owner (or such fiduciary, settlor, beneficiary, member, shareholder or possessor) being or having been a citizen or resident thereof or treated as a resident thereof or domiciled thereof or a national thereof or
being or having been present or engaged in trade or business therein or having or having had a permanent establishment therein; 
 (2) that
are estate, inheritance, gift, sales, transfer, personal property, wealth or similar taxes, duties, assessments or other governmental charges; 

(3) payable other than by withholding from payments in respect of a Guarantee; 

(4) that would not have been so imposed but for the failure of the applicable recipient of such payment to comply with any certification,
identification, information, documentation or other reporting requirement to the extent: 
 (i) such compliance is required
by applicable law or administrative practice or an applicable treaty as a precondition to exemption from, or reduction in, the rate of deduction or withholding of such Taxes; and 

(ii) at least thirty (30) days before the first payment date with respect to which such Additional Amounts shall be
payable, such Guarantor has notified such recipient in writing that such recipient is required to comply with such requirement; 
 (5) that
would not have been imposed but for the presentation of a Note (where presentation is required) for payment on a date more than thirty (30) days after the date on which such payment became due and payable or the date on which payment thereof
was duly provided for, whichever occurred later; 
 (6) that are imposed or withheld pursuant to Sections 1471 through 1474 of the U.S.
Internal Revenue Code of 1986, as amended (the “Code”), as of the issue date of the Notes (or any amended or successor version of such sections), any regulations promulgated thereunder, any official interpretations thereof, and any
similar law or regulation adopted pursuant to an intergovernmental agreement between a non-U.S. jurisdiction and the United States with respect to the foregoing or any agreements entered into pursuant to
Section 1471(b)(1) of the Code; 
 (7) that would not have been imposed if presentation for payment of the relevant Notes or a Guarantee
(where presentation is required), had been made to a paying agent other than the paying agent to which the presentation was made; or 

(8) any combination of the foregoing clauses (1) through (8); 

nor shall Additional Amounts be paid with respect to any payment in respect of a Guarantee, to any such Holder or beneficial owner who is a
fiduciary or a partnership or a beneficial owner who is other than the sole beneficial owner of such payment to the extent a beneficiary or settlor with respect to such fiduciary or a member of such partnership or a beneficial owner would not have
been entitled to such Additional Amounts had it been the Holder of the Note. 

  
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 (b) For avoidance of doubt, no Additional Amounts shall be paid with
respect to or on account of any present or future income, stamp or other tax, duty, levy, impost, assessment or other governmental charge of any nature whatsoever imposed or levied by or on behalf of the government of the United States or the United
Kingdom relating to payments by the Issuers under the Notes. 
 (c) All references in this Indenture, other than in Articles
Twelve or Thirteen of the Base Indenture, to the payment of the principal of or premium, if any, or interest, if any, on or the net proceeds received on the sale or exchange of, any Notes or any payment made under a Guarantee shall be deemed to
include Additional Amounts to the extent that, in that context, Additional Amounts are, were or would be payable in respect thereof. 

(d) The obligations of each Guarantor to pay Additional Amounts if and when due will survive the termination of this
Indenture and the payment of all other amounts in respect of the Notes.” 
 SECTION 3.06. Amendment to
Section 11.01—Company and Guarantors May Consolidate, etc., on Certain Terms. Section 11.01 of the Base Indenture is deleted in its entirety and is hereby replaced and superseded with the following provision: 

“Section 11.01. Company, the Co-Issuer and
Guarantors May Consolidate, etc., Only on Certain Terms. So long as any Securities shall be Outstanding, none of the Company, the Co-Issuer or, with respect to any series of Securities to which the
provisions of Article Fifteen shall apply, any Guarantor shall consolidate with or merge or convert into any other Person or convey, transfer or lease its properties and assets substantially as an entirety to any Person unless: 

(a) (1) The Company, the Co-Issuer or such Guarantor, as the case may be, is the
surviving entity, or (2) the Person formed by such consolidation or conversion or into which the Company, the Co-Issuer or such Guarantor, as applicable, is merged or converted or the Person which
acquires by conveyance or transfer, or which leases, the properties and assets of the Company, the Co-Issuer or such Guarantor, as the case may be, substantially as an entirety: 

(i) expressly assumes, by an indenture supplemental hereto, executed and delivered to the Trustee, in form satisfactory to
the Trustee, in the case of the Company and/or the Co-Issuer, the due and punctual payment of the principal of and premium, if any, and interest, if any, on all the Securities and the performance of every
covenant of this Indenture on the part of the Company and/or the Co-Issuer, as applicable, to be performed or observed or, in the case of such Guarantor, with respect to any series of Securities to which the
provisions of Article Fifteen shall apply, the due and punctual payment of all payment obligations under the Guarantee and the performance of every other covenant of this Indenture on the part of such Guarantor to be performed or observed and which
supplemental indenture shall provide for conversion or exchange rights in accordance with the provisions of the Securities of any series that are convertible or exchangeable into Shares or other securities, if any such Securities are then
outstanding; and 
 (ii) in the case of the Company, is a corporation or other entity organized and existing under the
laws of the United States, any State thereof or the District of Columbia. 

  
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 (b) immediately after giving effect to such transaction and treating any
indebtedness which becomes an obligation of the Company, the Co-Issuer or such Guarantor, as applicable, as a result of such transaction as having been incurred by the Company, the Co-Issuer or such Guarantor, as applicable, at the time of such transaction, no Event of Default, and no event which, after notice or lapse of time or both, would become an Event of Default, shall have happened and
be continuing; and 
 (c) the Company and/or the Co-Issuer, as applicable, has
delivered to the Trustee an Officers’ Certificate of the Company, the Co-Issuer or such Guarantor has delivered to the Trustee an Officers’ Certificate of such Guarantor, as the case may be, and, in
either case, an Opinion of Counsel, each stating that such consolidation, merger, conversion, conveyance, transfer or lease and, if a supplemental indenture is required in connection with such transaction, such supplemental indenture comply with
this Article and that all conditions precedent herein provided for relating to such transaction have been complied with.” 
 SECTION
3.07. Amendment to Section 11.02—Successor Person Substituted. Section 11.02 of the Base Indenture is deleted in its entirety and is hereby replaced and superseded with the following provision: 

“Section 11.02. Successor Person Substituted. So long as any Notes shall be
outstanding, upon any consolidation, merger or conversion, or any conveyance, transfer or lease of the properties and assets of the Company, the Co-Issuer or any Guarantor substantially as an entirety, in
accordance with Section 11.01, the successor Person formed by such consolidation or into which the Company, the Co-Issuer or such Guarantor, as applicable, is merged or converted or to which such
conveyance, transfer or lease is made shall succeed to, and be substituted for, and may exercise every right and power of, the Company, the Co-Issuer or such Guarantor, as the case may be, under this Indenture
with the same effect as if such successor Person had been named as the Company, the Co-Issuer or a Guarantor, as the case may be, herein, and thereafter, except in the case of a lease, the predecessor Person
shall be relieved of all obligations and covenants under this Indenture and the Notes.” 
 ARTICLE IV 

MISCELLANEOUS 
 SECTION 4.01.
Ratification. This Second Indenture Supplement shall be deemed part of the Base Indenture in the manner and to the extent herein provided. Except as expressly amended hereby, the Base Indenture is in all respects ratified and confirmed and
all the terms, conditions and provisions thereof shall remain in full force and effect. 
 SECTION 4.02. Provisions Binding on
Successors. All the covenants, stipulations, promises and agreements in this Second Indenture Supplement contained by or on behalf of the Company, the Co-Issuer or the Guarantors shall bind their
respective successors and assigns, whether so expressed or not. 
 SECTION 4.03. Counterparts. This Second Indenture Supplement may
be executed in any number of counterparts, each of which so executed shall be deemed an original, but all of such counterparts shall together constitute but one and the same instrument. 

  
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 SECTION 4.04. Governing Law. This Second Indenture Supplement shall be governed by
and construed in accordance with the laws of the State of New York, without regard to the principles of conflicts of laws. 
 SECTION 4.05.
Separability. In case any one or more of the provisions contained in this Second Indenture Supplement or in the Notes shall for any reason be held to be invalid, illegal or unenforceable in any respect, such invalidity, illegality or
unenforceability shall not affect any other provisions of this Second Indenture Supplement or of such Notes, but this Second Indenture Supplement and such Notes shall be construed as if such invalid or illegal or unenforceable provision had never
been contained herein or therein. 
 SECTION 4.06. Governing Law. This Second Indenture Supplement shall be governed by and construed
in accordance with the laws of the State of New York, without regard to the principles of conflicts of laws. 
 SECTION 4.07. Trustee.
The Trustee makes no representation as to the validity or sufficiency of this Second Indenture Supplement. The recitals contained herein shall be taken as the statements of the Company, the Co-Issuer and
the Trustee assumes no responsibility for their correctness. The Trustee shall have the right to accept and act upon instructions, including funds transfer instructions (“Instructions”) given pursuant to this Indenture and delivered
using Electronic Means; provided, however, that the Company and the Co-Issuer shall provide to the Trustee an incumbency certificate listing officers with the authority to provide such Instructions
(“Authorized Officers”) and containing specimen signatures of such Authorized Officers, which incumbency certificate shall be amended by the Company and the Co-Issuer whenever a person is to
be added or deleted from the listing. If the Company or the Co-Issuer elects to give the Trustee Instructions using Electronic Means and the Trustee in its discretion elects to act upon such Instructions, the
Trustee’s understanding of such Instructions shall be deemed controlling. The Each of the Company and the Co-Issuer understands and agrees that the Trustee cannot determine the identity of the actual
sender of such Instructions and that the Trustee shall conclusively presume that directions that purport to have been sent by an Authorized Officer listed on the incumbency certificate provided to the Trustee have been sent by such Authorized
Officer. The Company and the Co-Issuer shall be responsible for ensuring that only Authorized Officers transmit such Instructions to the Trustee and that the Company and the
Co-Issuer and all Authorized Officers are solely responsible to safeguard the use and confidentiality of applicable user and authorization codes, passwords and/or authentication keys upon receipt by the
Company and the Co-Issuer. The Trustee shall not be liable for any losses, costs or expenses arising directly or indirectly from the Trustee’s reliance upon and compliance with such Instructions
notwithstanding such directions conflict or are inconsistent with a subsequent written instruction. Each of the Company and the Co-Issuer agrees: (i) to assume all risks arising out of the use of
Electronic Means to submit Instructions to the Trustee, including without limitation the risk of the Trustee acting on unauthorized Instructions, and the risk of interception and misuse by third parties; (ii) that it is fully informed of the
protections and risks associated with the various methods of transmitting Instructions to the Trustee and that there may be more secure methods of transmitting Instructions than the method(s) selected by the Company or the Co-Issuer, as the case may be; (iii) that the security procedures (if any) to be followed in connection with its transmission of Instructions provide to it a commercially reasonable degree of protection in
light of its particular needs and circumstances; and (iv) to notify the Trustee immediately upon learning of any compromise or unauthorized use of the security procedures. The Trustee may execute this Second Indenture Supplement and any other
documents delivered pursuant hereto (including authentication of the Notes) via Electronic Means. 

  
 -11- 












 “Electronic Means” shall mean the following communications methods: S.W.1.F.T., e-mail, facsimile transmission, secure electronic transmission containing applicable authorization codes, passwords and/or authentication keys issued by the Trustee, or another method or system specified by the
Trustee as available for use in connection with its services hereunder. 
 [Signature Pages Follow] 

 

  
 -12- 












 IN WITNESS WHEREOF, each of the parties hereto has caused this Second Indenture Supplement
to be duly signed, all as of the day and year first above written. 
  

			
	AON CORPORATION, A CORPORATION DULY ORGANIZED AND EXISTING
UNDER THE LAWS OF THE STATE OF DELAWARE
		
	BY:	 	 /s/ Julie Cho

		 	NAME: JULIE CHO
		 	TITLE: VICE PRESIDENT AND SECRETARY
	
	AON GLOBAL HOLDINGS PLC, A PUBLIC LIMITED COMPANY DULY
ORGANIZED AND EXISTING UNDER THE LAWS OF ENGLAND AND WALES
		
	BY:	 	 /s/ Pelagia Katsaouni-Dodd

		 	NAME: PELAGIA KATSAOUNI-DODD 
		 	TITLE: DIRECTOR
	
	AON PLC, A PUBLIC LIMITED COMPANY DULY ORGANIZED AND
EXISTING UNDER THE LAWS OF IRELAND
		
	BY:	 	 /s/ Paul Hagy

		 	NAME: PAUL HAGY
		 	TITLE: TREASURER 
	
	AON GLOBAL LIMITED, A PRIVATE LIMITED COMPANY DULY ORGANIZED
AND EXISTING UNDER THE LAWS OF ENGLAND AND WALES
		
	BY:	 	 /s/ Rogier Sparreboom

		 	NAME: ROGIER SPARREBOOM
		 	TITLE: DIRECTOR


 [Company Signature Page to the Indenture Supplement] 











 
			
	THE BANK OF NEW YORK MELLON TRUST COMPANY, N.A.
		
	BY:	 	 /s/ Mitchell L. Brumwell

		 	NAME: MITCHELL L. BRUMWELL
		 	TITLE: VICE PRESIDENT


 [Trustee Signature Page to the Indenture Supplement] 

 











 EXHIBIT A 

FORM OF NOTE 
 Unless this
Security is presented by an authorized representative of The Depository Trust Company (55 Water Street, New York, New York) to the issuer or its agent for registration of transfer, exchange or payment, and any Security issued upon registration of
transfer of, or in exchange for, or in lieu of, this Security is registered in the name of Cede & Co. or such other name as requested by an authorized representative of The Depository Trust Company and any payment hereon is made to
Cede & Co., ANY TRANSFER, PLEDGE OR OTHER USE HEREOF FOR VALUE OR OTHERWISE BY OR TO ANY PERSON IS WRONGFUL since the registered owner hereof, Cede & Co., has an interest herein. 

AON CORPORATION 
 AON
GLOBAL HOLDINGS PLC 
 $                 % Senior
Notes due                      

with full and unconditional guarantees 

as to payment of principal and interest by 

Aon plc and Aon Global Limited 
  

			
	No. 	  	$            
	CUSIP No. 03740L AC6	  	

 AON CORPORATION 

AON GLOBAL HOLDINGS PLC 

Aon Corporation, a Delaware corporation (herein called the “Company,” which term includes any successor Person under the
Indenture hereinafter referred to) and Aon Global Holdings plc, a public limited company formed under the laws of England and Wales (hereinafter called the “Co-Issuer,” which term includes any
successor Person under the Indenture hereinafter referred to, and, together with the Company, the “Issuers”), for value received, hereby, jointly and severally, promise to pay to Cede & Co., as nominee for The Depository
Trust Company, or registered assigns, the principal sum of                      DOLLARS
($            ) on December 2, 2031 and, subject to Section 16.05 of said Indenture, to pay interest thereon from December 2, 2021 or from the most recent Interest Payment Date to
which interest has been paid or duly provided for, semi-annually in arrears on each June 2 and December 2, commencing June 2, 2022 (each, an “Interest Payment Date”), at the rate of 2.600% per annum, until the principal hereof is
paid or made available for payment. The interest so payable, and punctually paid or duly provided for, on any Interest Payment Date will, as provided in such Indenture, be paid to the Person in whose name this Security (or one or more predecessor
Securities) is registered at the close of business on the Regular Record Date for such interest, which shall be the June 2 or December 2 (whether or not a Business Day), as the case may be, immediately preceding such Interest Payment Date. Any such
interest not so punctually paid or duly provided for will forthwith cease to be payable to the Holder on such Regular Record Date and may either be paid to the Person in whose name this Security (or one or more predecessor Securities) is registered
at the close of business on a subsequent record date for the payment of such defaulted interest established by the Company and the Co-Issuer, notice whereof shall be given to Holders of Securities not less than 15 days prior to such subsequent
record date, such record date to be not less than 5 days preceding the date of payment of such defaulted interest, or be paid at any time in any other lawful manner not inconsistent with the requirements of any securities exchange on which the
Securities may be listed, and upon such notice as may be required by such exchange, all as more fully provided in said Indenture. 

  
 A-1 












 Payment of the principal of (and premium, if any) and any such interest on this Security
will be made at the office or agency of the Company maintained for that purpose in the City of Chicago or the Borough of Manhattan, The City of New York, in such coin or currency of the United States of America as at the time of payment is legal
tender for payment of public and private debts; provided, however, that at the option of the Company or the Co-Issuer payment of interest may be made by wire transfer, other electronic means or
mailing checks to the address of the Holder entitled thereto as such address shall appear in the Security Register. 
 The Securities are
subject to redemption and repurchase at the option of the Issuers prior to the stated maturity as described in the Indenture and on the reverse hereof. 

Reference is hereby made to the further provisions of this Security set forth on the reverse hereof, which further provisions shall for all
purposes have the same effect as if set forth at this place. 
 Unless the certificate of authentication hereon has been executed by the
Trustee referred to herein by manual or electronic signature, this Security shall not be entitled to any benefit under the Indenture or be valid or obligatory for any purpose. 

NOTICE TO HOLDER 
 THE HOLDER OF
THIS SECURITY IS HEREBY NOTIFIED, AND BY ITS ACCEPTANCE HEREOF ACKNOWLEDGES, THAT (1) THE COMPANY, THE CO-ISSUER AND A GUARANTOR, IN RESPECT OF ITS GUARANTEE, SHALL WITHHOLD OR DEDUCT FOR OR ON ACCOUNT OF
ANY PRESENT OR FUTURE INCOME, STAMP OR OTHER TAX, DUTY, LEVY, IMPOST, ASSESSMENT OR OTHER GOVERNMENTAL CHARGE OF ANY NATURE WHATSOEVER IMPOSED OR LEVIED BY OR ON BEHALF OF THE GOVERNMENT OF THE UNITED STATES OR BY ANY AUTHORITY OR AGENCY THEREIN OR
THEREOF HAVING THE POWER TO TAX (COLLECTIVELY, “UNITED STATES TAXES”) AS REQUIRED BY LAW OF THE UNITED STATES AND (2) IF THE COMPANY, THE CO-ISSUER OR A GUARANTOR (OR WITHHOLDING AGENT FOR THE
COMPANY, THE CO-ISSUER OR GUARANTOR) IS SO REQUIRED TO WITHHOLD OR DEDUCT ANY AMOUNT FOR OR ON ACCOUNT OF UNITED STATES TAXES FROM ANY PAYMENT, NO ADDITIONAL AMOUNTS SHALL BE PAID TO A HOLDER OR BENEFICIAL
OWNER FOR OR WITH RESPECT TO THE AMOUNT SO WITHHELD OR DEDUCTED. 

  
 A-2 












 IN WITNESS WHEREOF, the Company and the Co-Issuer
have caused this instrument to be duly executed. 
 Dated: 
  

			
	AON CORPORATION, A CORPORATION DULY ORGANIZED AND EXISTING
UNDER THE LAWS OF THE STATE OF DELAWARE
		
	By:	 	  

		 	Name: 
		 	Title: 
	
	AON GLOBAL HOLDINGS PLC, A PUBLIC LIMITED COMPANY DULY
ORGANIZED AND EXISTING UNDER THE LAWS OF ENGLAND AND WALES
		
	By:	 	  

		 	Name: 
		 	Title: 


  

	
	Attest:
	
	  

	Name: 
	Title: 

 [Company Signature Page to the Note] 











 This is one of the Securities of the series designated therein referred to in the
within-mentioned Indenture. 
  

							
		 		 	THE BANK OF NEW YORK MELLON TRUST COMPANY, N.A., as Trustee
				
	Dated:                     	 		 	By:	 	  

		 		 		 	Authorized Officer

 [Trustee Signature Page to the Note] 











 This Security is one of a duly authorized series of securities of the Company and the Co-Issuer entitled “2.600% Senior Notes due 2031” (herein called the “Securities”) issued and to be issued in one or more series under the Amended and Restated Indenture, dated
April 1, 2020, as supplemented by the Second Indenture Supplement, dated December 2, 2021, among the Company, the Co-Issuer, the Guarantors and The Bank of New York Mellon Trust Company, N.A., as
Trustee (herein called the “Trustee,” which term includes any successor trustee under the Indenture, as defined below) (together, the “Indenture”), to which Indenture and all indentures supplemental thereto
reference is hereby made for a statement of the respective rights, limitations of rights, duties and immunities thereunder of the Company, the Co-Issuer, the Trustee and the Holders of the Securities and of
the terms upon which the Securities are, and are to be, authenticated and delivered. The Securities of this series will initially be issued in the aggregate principal amount of $500,000,000. The Issuers may, from time to time, without the written
consent of or notice to holders of the Securities of this series, create and issue under the Indenture additional securities having the same terms and conditions as the Securities of this series (other than the issue date, the issue price and, to
the extent applicable, the first date from which interest on such additional securities shall accrue and the first interest payment date for such additional securities) and such additional securities shall be consolidated with and form a single
series with the Securities of this series. 
 At any time and from time to time prior to September 2, 2031 (such date, the “Par
Call Date”), the Issuers may at their option redeem all or some of the Securities of this series at a price equal to the greater of (1) 100% of the principal amount of the Securities to be redeemed and (2) the sum of the present values
of the remaining scheduled payments of principal and interest thereon (not including any portion of such payments of interest accrued as of the redemption date) from the redemption date to the Par Call Date, discounted to the date of redemption on a
semi-annual basis (assuming a 360-day year consisting of twelve 30-day months), at a rate equal to the sum of the applicable Treasury Rate (as defined below), plus 20
basis points (0.200%), plus, in each case, accrued and unpaid interest thereon to but excluding the redemption date (each such redemption being an “Optional Redemption”). 

At any time and from time to time on or after the Par Call Date, the Issuers may at their option redeem all or some of the Securities at a
redemption price equal to 100% of the principal amount of the Notes to be redeemed, plus accrued and unpaid interest thereon to but excluding the redemption date. 

If the Issuers have given notice of Optional Redemption as provided herein and in the Indenture and funds for the redemption of any Securities
of this series called for Optional Redemption have been made available on the applicable redemption date, such Securities will cease to bear interest on the date fixed for redemption. Thereafter, the only right of the Holders of such Securities will
be to receive payment of the applicable redemption price. 
 The Issuers will prepare and send a notice of an Optional Redemption to each
Holder of Securities to be redeemed by first-class mail at least 10 and not more than 60 calendar days prior to the date fixed for such Optional Redemption. On and after the redemption date for an Optional Redemption, interest will cease to accrue
on the Securities called for redemption (unless the Issuers or the Guarantors default in the payment of the redemption price). 

“Comparable Treasury Issue” means the U.S. Treasury security selected by the Quotation Agent as having a maturity comparable
to the remaining term of the Securities to be redeemed (assuming the Securities matured on the Par Call Date) that would be utilized, at the time of selection and in accordance with customary financial practice, in pricing new issues of corporate
debt securities of comparable maturity to the remaining term of the Securities (assuming the Securities matured on the Par Call Date). 

  
 A-5 












 “Comparable Treasury Price” means, with respect to any redemption date,
(i) the average of three Reference Treasury Dealer Quotations for such redemption date, after excluding the highest and lowest such Reference Treasury Dealer Quotations, or (ii) if the Quotation Agent is given fewer than five such
Reference Treasury Dealer Quotations, the average of all such quotations, or (iii) if only one Reference Treasury Dealer Quotation is received, such quotation. 

“Quotation Agent” means the Reference Treasury Dealer appointed by the Issuers. 

“Reference Treasury Dealer” means each of J.P. Morgan Securities LLC, BofA Securities, Inc. and Goldman Sachs & Co.
LLC (or their respective affiliates that are primary U.S. government securities dealers in New York City, each of which the Issuers refer to as a “Primary Treasury Dealer”) and their respective successors and two other nationally
recognized investment banking firms that are Primary Treasury Dealers appointed from time to time by the Issuers; provided, however, that if any of the foregoing shall cease to be a Primary Treasury Dealer, the Issuers will substitute therefor
another Primary Treasury Dealer. 
 “Reference Treasury Dealer Quotations” means, with respect to each Reference Treasury
Dealer and any redemption date, the average, as determined by the Quotation Agent, of the bid and asked prices for the Comparable Treasury Issue (expressed in each case as a percentage of its principal amount) quoted in writing to the Quotation
Agent by such Reference Treasury Dealer at 5:00 p.m., New York City time, on the third business day preceding such redemption date. 

“Treasury Rate” means, with respect to any redemption date, the rate per annum equal to the semi-annual equivalent yield to
maturity of the Comparable Treasury Issue, assuming a price for the Comparable Treasury Issue (expressed as a percentage of its principal amount) equal to the Comparable Treasury Price for such redemption date. 

All payments made by a Guarantor with respect to its Guarantee shall be made free and clear of and without withholding or deduction for or on
account of any present or future income, stamp or other tax, duty, levy, impost, assessment or other governmental charge of any nature whatsoever imposed or levied by or on behalf of the government of the United Kingdom or Ireland, as applicable,
or, in each case, by any authority or agency therein or thereof having the power to tax (collectively, “Taxes”), unless such Guarantor is required to withhold or deduct Taxes by law. 

If an Event of Default with respect to the Securities of this series shall occur and be continuing, the principal amount of and accrued and
unpaid interest, if any, on the Securities of this series may be declared due and payable in the manner and with the effect provided in the Indenture. 

The Indenture contains provisions for defeasance at any time of the entire indebtedness of this Security or certain restrictive covenants and
Events of Default with respect to this Security, in each case upon compliance with certain conditions set forth therein. 
 The Indenture
permits, with certain exceptions as therein provided, the amendment thereof and the modification of the rights and obligations of the Company and the Co-Issuer and the rights of the Holders of the Securities
of each series to be affected under the Indenture at any time by the Company, the Co-Issuer and the Trustee with the consent of the Holders of a majority in principal amount of the Securities at the time
Outstanding of each series to be affected. The Indenture also contains provisions permitting the Holders of specified percentages in principal amount of the Securities of each series at the time Outstanding, on behalf of the Holders of all
Securities of such series, to waive compliance by the Company and the Co-Issuer with certain provisions of the Indenture and certain past defaults under the Indenture and their consequences. Any such consent
or waiver by the Holder of this Security shall be conclusive and binding upon such Holder and upon all future Holders of this Security and of any Security issued upon the registration of transfer hereof or in exchange herefor or in lieu hereof,
whether or not notation of such consent or waiver is made upon this Security. 

  
 A-6 












 No reference herein to the Indenture and no provision of this Security or of the Indenture
shall alter or impair the obligation of the Company and the Co-Issuer, which is joint and several, absolute and unconditional, to pay the principal of and any premium and interest on this Security at the
times, place and rate, and in the coin or currency, herein prescribed. 
 As provided in the Indenture and subject to certain limitations
therein set forth, the transfer of this Security is registerable in the Security Register, upon surrender of this Security for registration of transfer at the office or agency of the Company or the Co-Issuer
in any place where the principal of and any premium and interest on this Security are payable, duly endorsed by, or accompanied by a written instrument of transfer in form satisfactory to the Company, the
Co-Issuer and the Security Registrar duly executed by, the Holder hereof or his attorney duly authorized in writing, and thereupon one or more new Securities of this series and of like tenor, of authorized
denominations and for the same aggregate principal amount, will be issued to the designated transferee or transferees. 
 The Securities of
this series are issuable only in registered form without coupons in denominations of $2,000 and integral multiples of $1,000. As provided in the Indenture and subject to certain limitations therein set forth, Securities of this series are
exchangeable for a like aggregate principal amount of Securities of this series and of like tenor of a different authorized denomination, as requested by the Holder surrendering the same. 

No service charge shall be made for any such registration of transfer or exchange, but the Issuers may require payment of a sum sufficient to
cover any tax or other governmental charge payable in connection therewith. 
 Prior to due presentment of this Security for registration of
transfer, the Company, the Co-Issuer, the Trustee and any agent of the Company, the Co-Issuer or the Trustee may treat the Person in whose name this Security is
registered as the owner hereof for all purposes, whether or not this Security be overdue, and none of the Company, the Co-Issuer, the Trustee or any such agent shall be affected by notice to the contrary. 

Interest on this Security shall be computed on the basis of a 360-day year consisting of twelve 30-day months. 
 All terms used but not defined in this Security which are defined in the Indenture shall
have the meanings assigned to them in the Indenture. 
 This Security shall be governed by and construed in accordance with the laws of the
State of New York without giving effect to the conflict of laws provisions thereof. 

  
 A-7 












 ASSIGNMENT 

I or we assign and transfer this Security to: 
  

					
		 	  
	  	

 (Insert assignee’s social security or tax I.D. number) 

 

					
		 	  
	  	

 (Print or type name, address and zip code of assignee) 

and irrevocably appoint: 
 as agent to transfer this Security on
the books of the Company and the Co-Issuer. The agent may substitute another to act for him. 
  

							
	Date:	  		  		  	
	                                      
                                         
             	  		  	Your	  	
		  		  	Signature:	  	  

				
		  		  		  	(Sign exactly as your name appears on the face of this Security)

 Signature 

Guarantee:             ________________________________________ 

Signatures must be guaranteed by an “eligible guarantor institution” meeting the requirements of the Security Registrar, which
requirements include membership or participation in the Security Transfer Agent Medallion Program (“STAMP”) or such other “signature guarantee program” as may be determined by the Security Registrar in addition to, or in
substitution for, STAMP, all in accordance with the Securities Exchange Act of 1934, as amended. 

  
 A-8 












 NOTATION OF GUARANTEE 

For value received, the undersigned Guarantor (which term includes any successor Person under the Indenture), subject to the provisions in the Indenture and
the terms of the Securities of this series, has fully, unconditionally and irrevocably guaranteed to and for the benefit of each Holder and the Trustee the due and prompt payment in full of all amounts which may at any time be or become from time to
time due and payable by the Company and the Co-Issuer under the Indenture or otherwise with respect to the Securities of this series registered in such Holder’s name, at their stated due dates or when
otherwise due in accordance with the terms thereof. The obligations of the Guarantor to the Holders of Securities and to the Trustee pursuant to the Guarantee under the Indenture are expressly set forth in Article Fifteen of the Indenture and
reference is hereby made to the Indenture for the precise terms of the Guarantee. Each Holder of a Security, by accepting the same, (a) agrees to and shall be bound by such provisions and (b) appoints the Trustee attorney-in-fact of such Holder for the purpose of such provisions. 
  

			
	Aon plc, a public limited company duly organized and existing under the laws of Ireland
		
	By:	 	  

		 	Name: Paul Hagy
		 	Title: Senior Vice President and Treasurer













 NOTATION OF GUARANTEE 

For value received, the undersigned Guarantor (which term includes any successor Person under the Indenture), subject to the provisions in the
Indenture and the terms of the Securities of this series, has fully, unconditionally and irrevocably guaranteed to and for the benefit of each Holder and the Trustee the due and prompt payment in full of all amounts which may at any time be or
become from time to time due and payable by the Company and the Co-Issuer under the Indenture or otherwise with respect to the Securities of this series registered in such Holder’s name, at their stated
due dates or when otherwise due in accordance with the terms thereof. The obligations of the Guarantor to the Holders of Securities and to the Trustee pursuant to the Guarantee under the Indenture are expressly set forth in Article Fifteen of the
Indenture and reference is hereby made to the Indenture for the precise terms of the Guarantee. Each Holder of a Security, by accepting the same, (a) agrees to and shall be bound by such provisions and (b) appoints the Trustee attorney-in-fact of such Holder for the purpose of such provisions. 
  

			
	Aon Global Limited, a private limited company duly organized and existing under the laws of England and Wales
		
	By:	 	  

		 	Name: Rogier Sparreboom
		 	Title:   Director