His parents' families included leading politicians and writers, among them Matthew Arnold, and his mother had been close to Rupert Brooke and his group as well as to Virginia Woolf.

Shortly after his birth, his parents went to live in a picturesque Cornish house, Eagle's Nest, in Zennor, Cornwall.

Instead, after a year's apprenticeship during 1938–39 with the Blue Funnel Line, involving a voyage to Manchuria, Arnold-Forster went on to join the Royal Navy.

Mark Arnold-Forster served throughout the Second World War, first as a merchant seaman and then in the Royal Navy Volunteer Reserve.

He later moved to ITN, as deputy to editor Sir Geoffrey Cox, making the switch to television without any difficulty.

Mark Arnold-Forster suffered from persistent ill health in his fifties, in particular a series of minor strokes.

In 1979, he developed cancer of the upper colon and died at his home, 50 Clarendon Road, Notting Hill, London, on Christmas Day, 1981.