His novels about 1950s British National Service such as "The Virgin Soldiers" spawned two film versions, in 1969 and 1977, whilst his Tropic of Ruislip and Dangerous Davies, The Last Detective have been adapted for television (the former as Tropic in 1979 and latter having also spawned a film version, in 1981).
His experiences as a British Army conscript in the Far East during the height of the Malayan emergency were recalled when he appeared the BBC Radio 2 documentary Caught In The Draft in 1985. Thomas joined ex-RAF national serviceman Bob Monkhouse and BBC Radio 2 drivetime presenter John Dunn in a programme filled with reminiscences about their years in uniform. The programme was written by Terence Pettigrew, produced by Harry Thompson and presented by Michael Aspel.
He was also featured in the short-lived BBC 1 show Time of My Life in 1983. The show was presented by Noel Edmonds and Thomas was reunited with National Service colleague Reg Wilcock for the first time in 32 years. They duetted a rendition of Tumbling Tumble weeds, a song they used to sing frequently on stage at The Liberty Club in Singapore.
Orphaned at the age of 12, Thomas was subsequently brought up in a Dr Barnardo's home; the story of this upbringing was the subject of his first, autobiographical, book, This Time Next Week.
In 1949, Thomas was called up for National Service and embarked on a two year tour of duty in Singapore with the Royal Army Pay Corps. While there he was briefly involved with the military action against communist rebels in Malaya (now Malaysia). He also began to write short articles for publication in English newspapers.
On his return to England in 1951, Thomas continued working for the local newspaper group in North London where he had worked before his National Service, but within 5 years he was working for The Exchange Telegraph news agency, now Extel, and eventually with the London Evening News newspaper, first as a sub-editor, later as a reporter. He stayed with the Evening News until 1965, when he embarked full-time on his writing career.
In 1984, Thomas published In My Wildest Dreams recounting his childhood in South Wales, his days in Doctor Barnardo's Homes in London, his National Service in the Far East, and his journalistic career.