Twelfth Amendment to Aon Pension Plan As Amended and Restated

Exhibit 10.3

Twelfth Amendment to Aon Pension Plan

As Amended and Restated Effective January 1, 2002

WHEREAS, the Aon Pension Plan (the “Plan”) is currently set out in the 2002 Restatement of the Aon Pension Plan, which was generally effective as of January 1, 2002 (the “Restatement”).

WHEREAS, the Board of Directors of Aon Corporation desires to amend the Plan pursuant to the authority to do so under Section 9.01 of the Plan to cease future benefit accruals after April 1, 2009.

NOW, THEREFORE, the Plan, as set out in the Restatement and as amended from time to time, is further amended as follows:

1.                                      Section 1.02 .  By adding the following provision at the end of Section 1.02, “Purpose”:

“Notwithstanding the foregoing, the future accrual of benefits under this Plan will cease effective