Stephens began his career as clerk in the victualling office where his elder brother was a commissioner. He was promoted to assistant secretary, and then became secretary to Lord Anson. In 1759 he was appointed second secretary to the Admiralty, and at Anson’s request was returned by Edward Eliot for Liskeard. In 1768 Stephens was returned for Sandwich on the Admiralty interest, and naturally supported each successive Administration. There is no record of his having spoken in the House during his 46 years as a Member.
His long service at the Admiralty was rewarded in 1795 with a baronetcy and a seat at the Admiralty Board; and in 1806, on leaving Parliament, he was given a pension of £1,500 a year.
He died 20 Nov. 1809.