Tavistock. The Duke of Bedford was lord lieutenant of Ireland and in 1757 Vernon became his second secretary.

He married Evelyn, Countess of Upper Ossory, the widow of John Fitzpatrick, 1st Earl of Upper Ossory and daughter of John Leveson-Gower, 1st Earl Gower on 15 February 1759. Soon after in May was given an Irish sinecure Clerk of