Halsey came of an old Hertfordshire family: his grandfather represented the county 1708-15; his father, a younger son, was a London merchant in the Hamburg trade, but in 1739 inherited the family estates on the death of his elder brother. Halsey himself followed his father into the Hamburg trade. In 1759 or before, as a member of the firm of Hanbury and Halsey, he went out to Hamburg, and in 1760 while still out there, was appointed a commissary of control to the army under Prince Ferdinand. His job was mainly to examine the execution of contracts, at a stipend of £3 a day. In 1762 he succeeded to the family estates on the death of his brother, and in February 1763 returned to England where he seems to have settled down as a country gentleman.
In 1768 he was returned unopposed for Hertfordshire. Before the election Sir John Sebright wrote to Lord Spencer, 15 Feb.:
His infirm state of health prevents him from all attention to his parliamentary duty, sometimes for a whole sessions together. This amiable character, however, in private life, has so endeared him to his constituents, that notwithstanding several gentlemen of the first opulence in the country have attempted to supplant him, and have promised a stricter attention to the duties of so important a trust; their efforts have, hitherto, proved totally nugatory ... Mr. Halsey resides mostly in the country, where his humanity and generosity, and a friendly familiar intercourse with his neighbours, have gained him the most universal esteem.
Halsey’s name appears in all the crucial divisions reported 1781-2, each time with Opposition. He voted for Shelburne’s peace preliminaries, 18 Feb. 1783, and for parliamentary reform, 7 May 1783, but was absent from the division on Fox’s East India bill, 27 Nov. 1783. Robinson in January 1784 classed him as ‘doubtful, desperate’, and Stockdale’s list as ‘Opposition’. He stood for Hertfordshire again in 1784, but was defeated.
He died 9 Oct. 1788, aged 57.
