He was First Commissioner of Woods and Forests under Lord Grey (1831-1834) and served under Lord Melbourne in that office (1835-1841), briefly as Home Secretary (1834), and as Lord Privy Seal (1835-1839).
His political career was hampered by a noted stammer, which made him a very reluctant public speaker: as Lord Duncannon he was unkindly nicknamed "Dumbcannon".