The Parliamentary Under-Secretary of State for Veterans and People is a ministerial position in the Ministry of Defence in British government, currently held by Alistair Carns.

[2] In a tweet, Mercer said he was "relieved of [his] responsibilities in Government" because of his disagreements with the scope of the proposed Overseas Operations Bill.

However, Mercer said it was a "red line" for him that British soldiers who served in Northern Ireland are excluded.

[5][6] On 7 July 2024, after the 2024 United Kingdom General Election Mercer criticised Sir Keir Starmer’s new Labour government for failing to appoint a new Minister of State for Veterans' Affairs at the same time as the rest of his cabinet.

He said; "You will note already that, despite his explicit personal promises in the election campaign, Keir Starmer has not appointed a veterans minister to his cabinet", adding, "If you understand what veterans need from their Government, this matters very much".