Exhibit 10.1

FIRST AMENDMENT TO THE

ARTHUR J. GALLAGHER & CO.

SEVERANCE PLAN

(effective September 15, 1997,

as amended and restated effective January 1, 2009)

WHEREAS, Arthur J. Gallagher & Co. (Illinois), an Illinois corporation (the
“Company”), maintains the Arthur J. Gallagher & Co. Severance Plan, effective
September 15, 1997, as amended and restated effective January 1, 2009 (the
“Plan”);

WHEREAS, pursuant to Section 8 of the Plan, the Company has reserved the power
to amend the Plan by an instrument in writing which has been executed on its
behalf by a duly authorized officer; and

WHEREAS, the Company desires to amend the Plan.

NOW, THEREFORE, pursuant to the power of amendment contained in Section 8 of the
Plan, the Plan is hereby amended as follows, effective June 1, 2010:

1. The following as added as the third full paragraph below the table in
Section 4 of the Plan:

“Notwithstanding anything to the contrary herein, if an employee employed by a
previous employer acquired by the Company is involuntarily terminated by an
Employer, as set forth in the Plan, prior to the first anniversary of the date
of such acquisition, the Vice President & Chief Human Resources Officer of the
Company may elect that the amount of severance pay payable under the Plan to
such employee shall be the lesser of (i) the amount set forth in the above table
or

--------------------------------------------------------------------------------

(ii) the amount that would have been payable to the employee under any severance
plan or arrangement of the previous employer applicable to the employee at the
time of such acquisition.”

2. The first paragraph of Section 5 of the Plan is deleted and replaced by the
following:

“Severance pay generally will be paid in a lump sum within 60 days after the
eligible employee’s date of termination of employment; provided that the seven
(7) day revocation period for a signed Waiver and General Release Agreement has
passed. The Employer reserves the right in its sole discretion to pay severance
pay in accordance with the Employer’s regular payroll payment schedule beginning
within 60 days after the eligible employee’s date of termination of employment
and payable only if the seven (7) day revocation period for a signed Waiver and
General Release Agreement has passed; provided that such discretion shall not
apply to any portion of severance pay that would be considered deferred
compensation within the meaning of Section 409A of the Internal Revenue Code of
1986, as amended (the “Code”) and further notwithstanding anything to the
contrary in this paragraph, in no event will severance be paid later than
March 15 of the year following the year in which an employee first becomes
eligible to receive severance under this Plan. All legally required taxes and
any sums owing to the Employer shall be deducted from Plan severance pay
payments.”

IN WITNESS WHEREOF, the Company has caused this Amendment to be executed by it’s
duly authorized officer this 1st day of June, 2010.

 

ARTHUR J. GALLAGHER & CO. (ILLINOIS) By:  

/s/ J. PATRICK GALLAGHER, JR.

  J. Patrick Gallagher, Jr.   President

 

Page 2 of 2