 He was promoted to captain in 1826 and went on half-pay.On 7 June 1827, he came off half-pay by exchanging into the 80th Regiment of Foot, and retired from the Army in 1830.Blayney entered the British House of Commons in 1830 as Tory Member of Parliament (MP) for Monaghan and held the seat until he succeeded his father as baron in 1834.