Son of a Russian-French father and a Polish-English mother, he was born into the world of the cultured bourgeoisie. His uncle was the pianist and conductor Leon Kartun (Stephane Grappelli was a violinist in his orchestra), while, on his mother's side, the writer Leon Garfield was his first cousin; his sister is Anita Pereire, doyenne of French garden writers.
His father had left the Paris Conservatoire when he realised that he would not be one of the great violinists of his generation, and became a successful designer and trader of jewellery. His parents' world was that of the international rich and glamorous, the luxury hotel and the ocean liner. One of Derek's earliest memories was sitting on the knee of Noel Coward as he played the piano. His father later made the regrettable decision not to finance Private Lives.
Kartun was sent to England for his schooling, first to a prep school in Redhill, Surrey, where the combination of being bookish, Jewish and French proved a hindrance to wide popularity, and then to St Paul's, where he flourished. By a cruel twist of fate, what should have been his sixth- form years coincided with a temporary reversal of his father's fortunes, and he was set to work in an advertising agency, sharing a desk with Eric Newby, and later found himself a job working on scripts for "B" movies for MGM, where he met the writer and journalist Claud Cockburn.
Bad eyesight confined him to civilian duties when war broke out in 1939. During the Second World War he became politicised and joined the Communist Party. He wrote several polemical books, including Tito's Plot Against Europe: the story of the Raik conspiracy (1949), This is America (1947) and Africa, Africa! (1954). He became foreign editor of the Daily Worker, and contributed to Cockburn's scurrilous news-sheet The Week. He covered the troubled birth of the state of Israel and was present during the Siege of Jerusalem in April 1948, typing his story on a typewriter rescued from the abandoned offices of The Times.
In 1949 he married Gwen Farrow, and their house in Kensington (demolished when the High Street was widened in the late Fifties; all that remains is an acacia tree, now in the pavement), with its alluring cocktail of good conversation, international sophistication and French cookery, became a natural meeting place of the leftist intelligentsia. Clancy Sigal, Mervyn Jones, Margot Heinemann and J.D. Bernal were in regular attendance, and Doris Lessing and Claud Cockburn were successively lodgers. Cockburn was amusing company but could be a worrying housemate, once leaving a tray laden with crockery on a lighted gas stove.
Growing disillusionment with Soviet Communism, brought to a head by Khrushchev's exposure of the crimes of Stalinism, and the brutal suppression of the Hungarian uprising in 1956, prompted Kartun to commute his Communist Party allegiance to Labour. Furthermore, now having two daughters, he realised that a career in politics was a luxury he could no longer afford.
He accepted the invitation of his friends Eddie Morgan and Harry Rose to join the board of a firm that had hit upon a way to streamline the mass-production of clothing. The firm, Staflex, was one of the notable business success stories of the Sixties and Seventies; Kartun became its managing director and later chairman. Its product, the fusible interlining, was used the world over, from Burton's suits to the uniforms of the Red Guards of China's cultural revolution.
After a couple of decades in business he was itching to get back to writing. He produced a series of spy thrillers: Beaver to Fox (1983), The Courier (1985), Flittermouse (1985), Megiddo (1987) and, with Vitali Vitaliev, The Third Trinity (1993); these met with a degree of success and were translated into several languages. His plays for BBC radio included one on the death of Tchaikovsky and one whose characters were the members of a string quartet, inspired by his long friendship with Siegmund Nissel of the Amadeus Quartet.
Derek Kartun was very broadly cultured: passionate about art and always eager to discuss the latest exhibitions, and widely read in English and French (with typical modesty saying that he was not a good linguist, but merely happened to speak French); his deep interest in music was centred on the classical and Romantic chamber repertoire.
He had a very warm human touch and could talk to anyone about anything; a natural teacher, he delighted in the company of the young. He had a particular knack of finding out about any unhappiness of a friend or colleague (down to the humblest member of the organisation), and made it his business to do what he could to put things right.
His Communism had no truck with the orthodoxy of the manifesto and the rulebook, but was a belief shot through with fellow-feeling for his brother man, a profound pity for the suffering of the downtrodden and oppressed and a quiet anger at the system which allowed it to happen.
Derek Isidore Kartun, writer, journalist and businessman: born Margate, Kent 9 August 1919; married 1949 Gwen Farrow (two daughters); died Chippenham, Wiltshire 11 January 2005.