#1 Class A Ordinary Shares granted annually to each non-employee director of Aon plc. In accordance with Irish law, reporting person agreed to pay the issuer the nominal value of US $0.01 per share issued to the reporting person.

#2 Class A Ordinary Shares withheld by the issuer for payment of taxes in connection with the award.

#1 Represents shares acquired pursuant to vesting of Performance Restricted Stock Units (RSU) that were granted to the reporting person in January 2021 and have vested based upon the satisfaction of performance criteria specified for the award at time of grant.

#2 The reported disposition represents the surrender of shares to satisfy tax obligations arising from the vesting of Restricted Stock Units.

#1 Represents shares acquired pursuant to vesting of Performance Restricted Stock Units (RSU) that were granted to the reporting person in January 2021 and have vested based upon the satisfaction of performance criteria specified for the award at time of grant.

#2 The reported disposition represents the surrender of shares to satisfy tax obligations arising from the vesting of Restricted Stock Units.

#1 The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $64.09 to $64.15, inclusive. The reporting person undertakes to provide to Hexcel Corporation, any security holder of Hexcel Corporation, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote.