Horace Trevor Cox was elected to Parliament as a Conservative in the 1937 Stalybridge and Hyde by-election and within a year was chosen to be PPS to Sir Ronald Cross, then Parliamentary under Secretary at the Board of Trade. Subsequently he followed Cross to the Ministry of Economic Warfare. However he enlisted in the Welsh Guards and served with the British Expeditionary Force in France in 1940. He narrowly escaped capture when Paris fell. On his return to England he served on the General Staff and in 1944 was appointed to the headquarters of AA Command as a Major. Returning to politics in 1945, he was appointed PPS to the Minister of Health, Sir Henry Willink, but lost his seat at the 1945 General Election. The victor was the man he had defeated at the by-election eight years earlier. Cox never returned to the Commons, but it was not for want of trying. His last attempt was made when he failed to secure selection to fight Salisbury in the 1965 by-election. He ran as an independent Conservative, lost his deposit, and subsequently abandoned the Conservative party to join the Labour Party. Although he stood for his local council in 1970 and three years later contested a County Council seat, he failed to secure election to either local authority. Thereafter he contented himself with service on the Salisbury Road Safety Committee, becoming its Chairman in 1985 and on the executive committee of the Country Landowners Association for Wiltshire, Hampshire and Berkshire.
Although he had been elected on an anti-Socialist platform, observing that wherever it had been tried, it had failed, his support for the National Government was based on its house building record and the major reduction in unemployment that had taken place since the Great Depression. By the time he switched parties, Labour was no longer particularly socialist and he was enthusiastic about Harold Wilson's leadership.
Horace Brimson Trevor Cox was born on 14 June 1908, the son of Horace Wilson of Whitby Hall, near Chester. He used Trevor as his first name to distinguish himself from his father and later in life included it as part of his surname. Many of his close friends knew him as T-C. He was educated at Eton, where he played football for the Eton Field and Wall Game in 1925 and 1926 and boxed for the school as a welterweight in 1925, 1926 and 1927. He was captain of games.
In the course of the next few years, he worked as a stoker on a transatlantic liner, as a cattle man and as an apprentice, studying commercial and political conditions in Germany 1927-9, in America and Canada 1929-30, and in Egypt and Palestine 1934. In 1935 he contested NE Derbyshire as a Conservative and two years later secured election as the Conservative MP for Stalybridge and Hyde. After his defeat in 1945 he served as Hon. Treasurer of the Russian Relief Association. He fought Birkenhead unsuccessfully in the 1950 election and served as the Conservative candidate for Romford in the run up to the 1955 election.
He inherited Roche Old Court at Winterslow from his father and in 1957 married his wife Gwenda. He had served on the county committee of the British Legion from 1946 until 1962 and chaired the Salisbury branch of the English Speaking Union from 1957-63. He must therefore have felt in a strong position to inherit the Salisbury seat, but it was denied him, apparently on the ground that at 56 he was too outside the required age range, Cox was bitterly angry at the decision, denounced the selection procedures used and attacked Central Office for trying to impose ex-Ministers on safe Conservative seats. But his reward for running as an independent was a derisory vote and his loss of patience with the Conservative party proved terminal.