Sir John "Jakie" Astor, who has died aged 82 after a long battle against Parkinson's disease, won distinction in his second and third careers after being vilified in his first. He won his 1978 knighthood for contributions to agriculture, partly from the success of his 1,900-acre farm at Hatley Park, Bedfordshire, but especially as chairman of the Agricultural Research Council. He won even wider plaudits for his key roles in the racing world, as a successful breeder with three establishments at Newmarket and many winners. He was a steward of the Jockey Club, and a member of the Tote and the Horserace Betting Levy Board, widely recognised for his outspoken good sense. Both these careers followed his rejection by the Conservative party for having been one of six Tory MPs who refused to support Sir Anthony Eden's 1956 invasion of Suez; like his older brother David, then editor of the Observer, he found it "unnecessary and wrong". Astor immediately found himself ostracised by his party and vilified by the Tory press. He discovered that the Conservatives were "not a party but a regiment", and announced he would not stand for the "family seat" of Plymouth-Sutton, which had been first occupied in 1910 by his father, William Astor, and then by his mother, Nancy Astor, the first woman to sit in the Commons. To be ostracised from any part of the establishment was a rare experience for an Astor. Although the first John Jacob Astor had been an 18th-century German migrant to the United States, he had made a fortune in the fur trade and invested it in Manhattan property - the basis of the Astor millions, even after his descendants transferred their affections to Britain, where they secured a barony and a viscountcy. Jakie himself was born at Cliveden, the youngest of the four sons of the 2nd Viscount Astor. He followed his father to Eton and New College, Oxford, where he first displayed his enthusiasm for racing. When he came of age, he received his first £1m from his grandfather's will. He joined the Life Guards, but soon transferred to the Phantom Regiment, and later to the SAS. Although the excitement of frontline service appealed, his skills with signals equipment gave him key supporting roles in the 1942 commando raid on Dieppe, as a signals officer on a supporting destroyer. He ended the war as a major, with a military MBE, a Legion d'Honneur and a Croix de Guerre. On demobilisation, partly to please his mother, he agreed to fight her old Plymouth-Sutton seat. He failed by 924 votes in 1950 but succeeded by 710 in 1951, when the Conservatives returned to office. In the Commons, Jakie showed himself to be a liberal Tory, aligned with Peter Thorneycroft and RA Butler, and was one of the first MPs from his party to oppose capital punishment. He also sought to legalise gambling, and was an early pro-European. He married three times, first in 1944 to the late Ana-Ines Carcano, daughter of the Argentine ambassador; they parted in 1972. In 1976 he married Susan Sheppard; they parted in 1995. Then, in 1988, he married Marcia de Savary, who survives him, together with a son and daughter from his first marriage.