Langston’s father, a successful wine merchant, was deputy governor of the Bank of England (1775-6) and a year later founded the London bank of Langston, Towgood and Amory in Cheapside. It was said to be worth ‘half a million stirling’ at his death. To his son he left £300,000 and the Sarsden and Churchill estates in Oxfordshire, purchased in 1791, as well as a partnership in the bank and East India Company stock. In an election squib of 1796 (‘Minehead Races’) Langston junior was dubbed ‘Vintner ... got by that well known drag-horse "Jerusalem John" out of a famous old taphouse mare called "Gill of Wine" ’.
Langston was prepared from the outset to buy his way into Parliament: but quiet seats eluded him. As Member for Sudbury, after a contest, he gave a silent support to Pitt’s administration. In 1790 he joined forces with the Poulett interest at Bridgwater and was returned on a poll. He is not know to have broken silence in the House, but in 1791 he was listed among opponents of the repeal of the Test Act in Scotland. In 1794 his name began to appear in the minority. On 8 Apr. he voted for Harrison’s motion to tax placemen and pensioners. On 30 Dec. he voted for Wilberforce’s amendment in favour of peace negotiations and he voted in the same sense on 26 Jan. 1795. On 5 Feb. he opposed the imperial loan; on 24 Mar. supported Fox’s motion in the state of the nation; on 27 May voted for Wilberforce’s fresh bid for peace negotiations, and on 1 June was in the minority on the Prince of Wale’s debts. He further supported Grey’s motions of 15 Feb. and 10 Mar. 1796 for peace negotiations and for an inquiry into the national finances. He oposed the abolition of the slave trade, 15 Mar.
Langston’s conduct put him out of the question at Bridgwater at the election of 1796. Instead he laid siege to the close borough of Minehead, controlled by John Fownes Luttrell I, with his wife’s brother-in-law, Charles Morice Pole, as running partner. Luttrell at first refused a compromise, but was so unpopular that Langston defeated his brother for second place: Luttrell had to be satisfied with a compromise to hold on to his own. Langston remained selectively critical of government, though he subscribed £10,000 to the loyalty loan for 1797. On 28 Feb. and 1 Mar. 1797 he voted with opposition on the stoppage of Bank payments. Two of his partners had been arrested for refusal to pay in specie, and at the London bankers’ meeting in March he called for legislative protection for bankers in this respect.
Langston was out of the House until March 1806, whenon the advent of the Grenville administration he came in for an Irish borough vacated by the Prince of Wales’s friend Thomas Tyrwhitt, on Lord Portarlington’s interest. He was clearly a supporter of the ministry—by now ’friendly’ to the abolition of the slave trade. On 2 Mar. 1807 he was a defaulter, but he voted for Brand’s motion against the new ministry on 9 Apr. At the general election of 1806 he had successfully contested Bridgwater, in conjunction with Earl Poulett’s brother, another friend of the ministry. In 1807 he withdrew, complaining of the ’No Popery’ cry against him. It was his last fling. In 1811 his bank was merged in another, Rogers & Co. He died 11 Feb. 1812, after a long illness.