Viscount Strangford was a title in the Peerage of Ireland. It was created in for Sir Thomas Smythe. He was a son of John Smith (also Smythe) J.P., High Sheriff of Kent 1600–1601, also M.P. for Aylesbury (in 1584) and Hythe (in 1586, 1587 and 1604), and grandson of Thomas Smythe, of Westenhanger Castle, collector of customs for London, haberdasher, and M.P.
The sixth Viscount was British ambassador to Portugal, Sweden, the Ottoman Empire and Russia. In 1825 he was created Baron Penshurst, of Penshurst in the County of Kent, in the Peerage of the United Kingdom, enabling him and his descendants to sit in the House of Lords. He was succeeded by his eldest son, the seventh Viscount. He was a Conservative politician, best known for his association with Benjamin Disraeli and the Young England movement. He died young and was succeeded by his younger brother, the eighth Viscount. He was a man of letters. The titles became extinct on his death in, although his widow, Viscountess Strangford, lived until 1887.