Exhibit 4.3


 


FORM OF LOCK-UP AGREEMENT (SPONSOR)


 


THIS LOCK-UP AGREEMENT (this
 “Agreement”) is made and entered into as of September 3, 2021 between (i) Arqit Quantum Inc., a Cayman Islands
exempted limited liability company (“Pubco”) and (ii) the undersigned (the “Holder”). Pubco and
the Holder are sometimes referred to herein individually as a “Party” and, collectively, as the “Parties”.
Any capitalized term used but not defined in this Agreement will have the meaning ascribed to such term in the Business Combination Agreement
(as defined below).


 


WHEREAS, Centricus Acquisition
Corp., Pubco and Arqit Limited, among others, entered into a business combination agreement, dated May 12, 2021 (the “Business
Combination Agreement”), pursuant to which the parties thereto shall consummate a series of transactions, including the exchange
of all of the Purchaser Ordinary Shares owned by the Holder into a corresponding number of Pubco Ordinary Shares determined in accordance
with the Business Combination Agreement.


 


WHEREAS, pursuant to the
Business Combination Agreement, and in view of the valuable consideration to be received by the Holder thereunder, Pubco and the Holder
desire to enter into this Agreement, pursuant to which the Pubco Ordinary Shares to be received by the Holder pursuant to the Business
Combination Agreement (together with any securities paid as dividends or distributions with respect to such securities or into which such
securities are exchanged or converted, the “Restricted Securities”) shall become subject to limitations on disposition
as set forth herein.


 


NOW, THEREFORE, in
consideration of the premises set forth above, which are incorporated in this Agreement as if fully set forth below, and intending to
be legally bound hereby, the Parties hereby agree as follows:


 


1.                  
Lock-Up Provisions.


 


(a)                
The Holder agrees that it shall not effectuate a Transfer of the Pubco Ordinary Shares that are held by the Holder during the period
commencing from the Share Acquisition Closing until the earlier to occur of (i) the date on which the
closing price of the Pubco Ordinary Shares during such period exceeds Twelve Dollars Fifty Cents ($12.50) per share (as adjusted for share
splits, share dividends, reorganizations and recapitalizations) for any twenty (20) trading days during a thirty (30) consecutive trading
day period and (ii) eighteen (18) months after the Share Acquisition Closing (the “Lock-up Period”).


 


(b)                Notwithstanding
the provisions set forth in Section 1(a), Transfers of the Pubco Ordinary Shares that are held by the Holder (and that have complied
with this Section 1(b)) are permitted (i) to Pubco’s officers or directors, any Affiliates or immediate family members of any
of Pubco’s officers or directors, any members of the Holder, or any Affiliates of the Holder, (ii) to shareholders or limited
partners of the Holder, or, in the case of a Holder which is a limited liability partnership, its members, (iii) by gift to a
member of the Holder’s immediate family or to a trust, the beneficiary of which is a member of the Holder’s immediate
family, an Affiliate of such person or to a charitable organization, (iv) by virtue of the laws of descent and distribution upon
death, (v) pursuant to a qualified domestic relations order or in connection with a divorce settlement, (vi) to (A) any UK
Government departments, including their executive agencies, other subsidiary bodies and other parts of UK Government; (B) companies
wholly or partly owned by UK Government departments and their subsidiaries; (C) non-departmental public bodies, other public bodies,
public corporations and their subsidiary bodies sponsored by UK Government departments; and/or (D) any successors to any of the
entities set out in (A), (B) and (C) above or any new bodies which fall within the same criteria (vii) by virtue of the laws of the
Holder’s jurisdiction of incorporation or organization, the Holder’s organizational documents or the rights attaching to
the equity interests in the Holder upon dissolution of the Holder, (viii) the exercise of any options, warrants or other convertible
securities to purchase Pubco Ordinary Shares (which exercises may be effected on a cashless basis to the extent the instruments
representing such options or warrants permit exercises on a cashless basis); provided, that any Pubco Ordinary Shares issued
upon such exercise shall be subject to the Lock-Up Period, (ix) to satisfy tax withholding obligations pursuant to the
Holder’s equity incentive plans or arrangements, (x) in connection with any bona fide mortgage, pledge or encumbrance to a
financial institution in connection with any bona fide loan or debt transaction or enforcement thereunder, including foreclosure
thereof, (xi) by a Holder to any entity including without limitation any fund, partnership, company or investment trust to whom the
Holder transfers interests in one or more of its portfolio of investments, or any successor entity following a restructuring
transaction of that Holder and (xii) in connection with a transfer pursuant to a bona fide third party
tender offer, merger, consolidation or other similar transaction made to all Holders of Pubco Ordinary Shares involving a change of
control of Pubco, provided, that in clauses (i) through (xi), the transferee must enter into a written agreement in
substantially the form of this Agreement, agreeing to be bound by the terms of the Lock-up Period. If dividends are declared and
payable in Pubco Ordinary Shares, such dividends will also be subject to the Lock-up Period.


 






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(c)                
If any Transfer is made or attempted contrary to the provisions of this Agreement, such Transfer shall be null and void ab initio,
and Pubco shall refuse to recognize any such transferee of the Restricted Securities as one of its equity holders for any purpose. In
order to enforce this Section 1, Pubco may impose stop-transfer instructions with respect to the Restricted Securities of the Holder
(and any permitted transferees and assigns thereof) until the end of the Lock-Up Period.


 


(d)               
During the Lock-Up Period, each certificate evidencing any Restricted Securities (if any are issued) shall be stamped or otherwise
imprinted with a legend in substantially the following form, in addition to any other applicable legends:


 


“THE SECURITIES REPRESENTED BY THIS
CERTIFICATE ARE SUBJECT TO RESTRICTIONS ON TRANSFER SET FORTH IN A LOCK-UP AGREEMENT, DATED AS OF SEPTEMBER 3, 2021, BY AND AMONG THE
ISSUER OF SUCH SECURITIES (THE “ISSUER”) AND THE ISSUER’S SECURITY HOLDER NAMED THEREIN, AS AMENDED. A COPY OF
SUCH LOCK-UP AGREEMENT WILL BE FURNISHED WITHOUT CHARGE BY THE ISSUER TO THE HOLDER HEREOF UPON WRITTEN REQUEST.”


 


(e)                
For the avoidance of any doubt, the Holder shall retain all of its rights as a shareholder of Pubco with respect to the Restricted
Securities during the Lock-Up Period, including the right to vote any Restricted Securities.


 


(f)                 
For the purposes of this Section 1, “Transfer” shall mean the (a) sale of, offer to sell, contract or agreement to
sell (including, for the avoidance of doubt, through a distribution in specie), hypothecate, pledge, grant of any option to purchase or
otherwise dispose of or agreement to dispose of, directly or indirectly, or establishment or increase of a put equivalent position or
liquidation with respect to or decrease of a call equivalent position within the meaning of Section 16 of the Securities Exchange Act
of 1934, as amended, and the rules and regulations of the U.S. Securities and Exchange Commission promulgated thereunder with respect
to, any security, (b) entry into any swap or other arrangement that transfers to another, in whole or in part, any of the economic consequences
of ownership of any security, whether any such transaction is to be settled by delivery of such securities, in cash or otherwise, or (c)
public announcement of any intention to effect any transaction specified in clause (a) or (b).


 


2.                  
Miscellaneous.


 


(a)                
Effective Date. Section 1 of this Agreement shall become effective upon the Share Acquisition Closing, subject to the consummation
of the transactions contemplated by the Business Combination Agreement on the Share Acquisition Closing Date.


 


(b)               
Termination of the Business Combination Agreement. Notwithstanding anything to the contrary contained herein, in the event
that the Business Combination Agreement is terminated in accordance with its terms prior to the Share Acquisition Closing, this Agreement
and all rights and obligations of the Parties hereunder shall automatically terminate and be of no further force or effect.


 


(c)                
Binding Effect; Assignment. This Agreement and all of the provisions hereof shall be binding upon and inure to the benefit
of the Parties hereto and their respective permitted successors and assigns. Except as otherwise provided in this Agreement, this Agreement
and all obligations of the Parties are personal to the Parties and may not be transferred or delegated by the Parties at any time.


 






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(d)               
 Third Parties. Nothing contained in this Agreement or in any instrument or document executed by any party in connection
with the transactions contemplated hereby shall create any rights in, or be deemed to have been executed for the benefit of, any person
or entity that is not a Party hereto or thereto or a successor or permitted assign of such a Party.


 


(e)                
Governing Law; Jurisdiction. This Agreement shall be governed by and construed in accordance with the Laws of the State
of Delaware, without giving effect to any choice of Law or conflict of Law provision or rule (whether of the State of Delaware or any
other jurisdiction) that would cause the application of the law of any jurisdiction other than the State of Delaware. Each Party (a) irrevocably
consents to the service of the summons and complaint and any other process in any action or proceeding relating to the transactions contemplated
by this Agreement, for and on behalf of itself or any of its properties or assets, in accordance with this Section 2(e) or in such other
manner as may be permitted by applicable Law, that such process may be served in the manner of giving notices in Section 2(h) and that
nothing in this Section 2(e) shall affect the right of any Party to serve legal process in any other manner permitted by applicable Law,
(b) irrevocably and unconditionally consents and submits itself and its properties and assets in any action or proceeding to the exclusive
general jurisdiction of the Court of Chancery of the State of Delaware (the “Chancery Court”) and any state appellate
court therefrom located within the State of Delaware (or, only if the Chancery Court declines to accept jurisdiction over a particular
matter, any state or federal court within the State of Delaware) in the event any dispute or controversy arises out of this Agreement
or the transactions contemplated hereby, or for recognition and enforcement of any Order in respect thereof, (c) agrees that it will not
attempt to deny or defeat such personal jurisdiction by motion or other request for leave from any such court, (d) agrees that any actions
or proceedings arising in connection with this Agreement or the transactions contemplated hereby shall be brought, tried and determined
only in the Chancery Court and any state appellate court therefrom located within the State of Delaware (or, only if the Chancery Court
declines to accept jurisdiction over a particular matter, any state or federal court within the State of Delaware), (e) waives any objection
that it may now or hereafter have to the venue of any such action or proceeding in any such court or that such action or proceeding was
brought in an inconvenient court and agrees not to plead or claim the same, and (f) agrees that it will not bring any action or proceeding
relating to this Agreement or the transactions contemplated hereby in any court other than the aforesaid courts. Each Party agrees that
a final Order in any action or proceeding in such courts as provided above shall be conclusive and may be enforced in other jurisdictions
by suit on the Order or in any other manner provided by applicable Law.


 


(f)                 
WAIVER OF JURY TRIAL. EACH OF THE PARTIES HERETO HEREBY WAIVES TO THE FULLEST EXTENT PERMITTED BY APPLICABLE LAW ANY RIGHT
IT MAY HAVE TO A TRIAL BY JURY WITH RESPECT TO ANY ACTION DIRECTLY OR INDIRECTLY ARISING OUT OF, UNDER OR IN CONNECTION WITH THIS AGREEMENT
OR THE TRANSACTIONS CONTEMPLATED HEREBY. EACH PARTY HERETO (i) CERTIFIES THAT NO REPRESENTATIVE OF ANY OTHER PARTY HAS REPRESENTED, EXPRESSLY
OR OTHERWISE, THAT SUCH OTHER PARTY WOULD NOT, IN THE EVENT OF ANY ACTION, SEEK TO ENFORCE THAT FOREGOING WAIVER AND (ii) ACKNOWLEDGES
THAT IT AND THE OTHER PARTIES HERETO HAVE BEEN INDUCED TO ENTER INTO THIS AGREEMENT BY, AMONG OTHER THINGS, THE MUTUAL WAIVERS AND CERTIFICATIONS
IN THIS SECTION 2(e).


 


(g)               
Interpretation. The titles and subtitles used in this Agreement are for convenience only and are not to be considered in
construing or interpreting this Agreement. In this Agreement, unless the context otherwise requires: (i) any pronoun used in this Agreement
shall include the corresponding masculine, feminine or neuter forms, and the singular form of nouns, pronouns and verbs shall include
the plural and vice versa; (ii) “including” (and with correlative meaning “include”) means including without limiting
the generality of any description preceding or succeeding such term and shall be deemed in each case to be followed by the words “without
limitation”; (iii) the words “herein,” “hereto,” and “hereby” and other words of similar import
in this Agreement shall be deemed in each case to refer to this Agreement as a whole and not to any particular section or other subdivision
of this Agreement; and (iv) the term “or” means “and/or”. The Parties have participated jointly in the negotiation
and drafting of this Agreement. Consequently, in the event an ambiguity or question of intent or interpretation arises, this Agreement
shall be construed as if drafted jointly by the Parties hereto, and no presumption or burden of proof shall arise favoring or disfavoring
any party by virtue of the authorship of any provision of this Agreement.


 






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(h)               
 Notices. All notices, consents, waivers and other communications hereunder shall be in writing and shall be deemed to have
been duly given when delivered (i) in person, (ii) by e-mail (having obtained electronic delivery confirmation thereof), (iii) one (1)
Business Day after being sent, if sent by reputable, nationally recognized overnight courier service or (iv) three (3) Business Days after
being mailed, if sent by registered or certified mail, pre-paid and return receipt requested, provided, however, that notice
given pursuant to clauses (iii) and (iv) above shall not be effective unless a duplicate copy of such notice is also given in person or
by e-mail (having obtained electronic delivery confirmation thereof), in each case to the applicable Party at the following addresses
(or at such other address for a Party as shall be specified by like notice):


 


	
     

    If to Pubco, to:

     

    Arqit Quantum Inc.

    c/o Maples Corporate Services Limited

    PO Box 309, Ugland House

    Grand Cayman, KY1-1104

    Cayman Islands

    United Kingdom

    Attn: David Williams

    Email: dw@arqit.uk

     
	
     

    With a copy to (which shall not constitute
    notice):

     

    White & Case LLP

    5 Old Broad Street

    London EC2N 1DW

    United Kingdom

    Attention: Elliott Smith, Daniel Turgel and Monica
    Holden

    Email: elliott.smith@whitecase.com, daniel.turgel@whitecase.com,
    mholden@whitecase.com

     

	
     

    If to the Holder, to:  the address
    set forth under the Holder’s name on the signature page hereto.

     



 


(i)                 
Amendments and Waivers. Any term of this Agreement may be amended and the observance of any term of this Agreement may be
waived (either generally or in a particular instance, and either retroactively or prospectively) only with the written consent of Pubco
and the Holder. No failure or delay by a Party in exercising any right hereunder shall operate as a waiver thereof. No waivers of or exceptions
to any term, condition, or provision of this Agreement, in any one or more instances, shall be deemed to be or construed as a further
or continuing waiver of any such term, condition, or provision.


 


(j)                 
Severability. In case any provision in this Agreement shall be held invalid, illegal or unenforceable in a jurisdiction,
such provision shall be modified or deleted, as to the jurisdiction involved, only to the extent necessary to render the same valid, legal
and enforceable, and the validity, legality and enforceability of the remaining provisions hereof shall not in any way be affected or
impaired thereby nor shall the validity, legality or enforceability of such provision be affected thereby in any other jurisdiction. Upon
such determination that any term or other provision is invalid, illegal or incapable of being enforced, the Parties will substitute for
any invalid, illegal or unenforceable provision a suitable and equitable provision that carries out, so far as may be valid, legal and
enforceable, the intent and purpose of such invalid, illegal or unenforceable provision.


 


(k)               
Specific Performance. The parties hereto agree that irreparable damage would occur in the event that any of the provisions
of this Agreement were not performed in accordance with their specific terms or were otherwise breached. The parties further agree that
each party shall be entitled to seek specific performance of the terms hereof and immediate injunctive relief and other equitable relief
to prevent breaches, or threatened breaches, of this Agreement, without the necessity of proving the inadequacy of money damages as a
remedy and without bond or other security being required, this being in addition to any other remedy to which they are entitled at law
or in equity. Each party hereby acknowledges and agrees that it may be difficult to prove damages with reasonable certainty, that it may
be difficult to procure suitable substitute performance, and that injunctive relief and/or specific performance will not cause an undue
hardship to the parties. Each party hereby further acknowledges that the existence of any other remedy contemplated by this Agreement
does not diminish the availability of specific performance of the obligations hereunder or any other injunctive relief. Each party hereby
further agrees that in the event of any action by any other party for specific performance or injunctive relief, the first party will
not assert that a remedy at law or other remedy would be adequate or that specific performance or injunctive relief in respect of such
breach or violation should not be available on the grounds that money damages are adequate or any other grounds.


 






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(l)                 
 Entire Agreement. This Agreement constitutes the full and entire understanding and agreement among the Parties with respect
to the subject matter hereof, and any other written or oral agreement relating to the subject matter hereof existing between the Parties
is expressly canceled; provided, that, for the avoidance of doubt, the foregoing shall not affect the rights and obligations
of the Parties under the Business Combination Agreement or any Ancillary Document. Notwithstanding the foregoing, nothing in this Agreement
shall limit any of the rights, remedies or obligations of the Parties under any other agreement between the Holder and Pubco or any certificate
or instrument executed by the Holder in favor of Pubco, and nothing in any other agreement, certificate or instrument shall limit any
of the rights, remedies or obligations of the Parties under this Agreement.


 


(m)              
Further Assurances. From time to time, at another Party’s request and without further consideration (but at the requesting
Party’s reasonable cost and expense), each Party shall execute and deliver such additional documents and take all such further action
as may be reasonably necessary to consummate the transactions contemplated by this Agreement.


 


(n)               
Counterparts; Facsimile.  This Agreement may also be executed and delivered by facsimile signature or by email in portable
document format in two or more counterparts, each of which shall be deemed an original, but all of which together shall constitute one
and the same instrument.


 


 


[Remainder of Page Intentionally Left Blank;
Signature Pages Follow]





 






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 IN WITNESS WHEREOF, the parties have
executed this Lock-Up Agreement as of the date first written above.


 


	 	Pubco:
	 	 
	 	Arqit Quantum Inc.
	 	 
	 	By:	     
	 	Name: David Williams
	 	Title: Director




 


[Signature Page to Lock-up
Agreement] 


 






     


     


    

 





IN WITNESS WHEREOF, the
parties have executed this Lock-Up Agreement as of the date first written above. 


 


	Holder:	 
	 	 
	Name of Holder: Centricus Heritage LLC	 
	 	 
	By:	        	 
	Name: Cristina Levis	 
	Title: Manager	 
	 	 
	Notice Information:	 
	Address:	 
	 	 
	E-mail:	 




 


[Signature Page to Lock-up
Agreement]