William Holmes was born in 1779 in Ireland.
Holmes initially joined the army, but from 1808 he started a career in politics. During his career Holmes acted as a Tory whip and his Charles Street headquarters became the Carlton Club. Whips were normally appointed to the post of lord of the Treasury, but unusually Holmes was appointed to the post of Treasurer to the Ordnance from 1818 until 1830. Nicknamed ‘Black Billy’, Holmes was an ultra Tory and stringent Protestant.
He died at home in Grafton Street in 1851.