His acting career began at the age of 16 at the Birmingham Repertory Theatre in 1921. He appeared in many repertory shows until he went to Canada where he worked on a cattle ranch for a year.

Newton was put under contract to Alexander Korda who cast him in small roles in the cinema films Fire Over England (1937), Dark Journey (1937), Farewell Again (1937) and The Squeaker (1937). He also had a part as Cassius in the abandoned version of I, Claudius and in 21 Days (shot in 1937, released 1940). Newton was borrowed by 20th Century Fox for The Green Cockatoo (1937). Newton had a good role supporting Charles Laughton in Vessel of Wrath (1938). He had another strong part in Yellow Sands (1939) and had his first film lead in Dead Men Are Dangerous (1939). He made another with Laughton, Jamaica Inn (1939), playing the romantic male lead, directed by Alfred Hitchcock. In 1939, he played Horatio to Laurence Olivier’s Hamlet at the Old Vic, in a production that included Alec Guinness and Michael Redgrave. Newton kept busy as a film actor, appearing in Poison Pen (1939) and Hell’s Cargo (1939).

Newton enlisted in the Royal Navy and saw active service in the rank of an Able Seaman on board HMS Britomart, which fought as an escort ship on several Russian convoys. After two and a half years in the Royal Navy he was medically discharged in 1943.

His final performance on stage was in the 1950 production of Gaslight with Rosamund John at the Vaudeville Theatre.

Treasure Island’s success prompted Newton to relocate to Hollywood. He was one of several British actors in Soldiers Three (1951), an Imperial adventure tale. He returned to Britain for Tom Brown’s Schooldays (1951) to play Thomas Arnold, then was cast by 20th Century Fox as Javert in their version of Les Misérables (1952). In 1951 he was voted the sixth most popular British star in Britain.

Newton married four times and had three children: Sally Newton (born 1930), Nicholas Newton (born 1950) and Kim Newton (born 1953). He was accused of kidnapping his son when he took him to Hollywood in 1951, the year his third marriage ended. He married his fourth wife, Vera Budnick, in June 1952. They had a son, Kim, born 1953. After a court battle, Newton’s elder son was placed in the custody of his aunt and uncle.

Back in Britain, Newton was given the lead in The Beachcomber (1954), a remake of Vessels of Wrath, this time in the part originally played by Charles Laughton. He again played Long John Silver in a 1954 Australian-made film, Long John Silver. It was shot at Pagewood Studios, Sydney and directed by Byron Haskin, who had directed Treasure Island. The company went on to make a 26-episode 1955 TV series, The Adventures of Long John Silver, in which Newton also starred. Earlier in 1954 he quit the film Svengali for personal reasons to be replaced by Sir Donald Wolfit which left him open to a legal action and, while filming in Australia in 1954, this led to Newton being declared bankrupt with unpaid tax in the UK of £47,000.

His last screen appearance was as ‘Inspector Fix’ in Around the World in 80 Days (1956) opposite David Niven, Shirley MacLaine and the Mexican star Cantinflas. It won the Academy Award for the Best Picture in 1956.

Newton suffered in the latter part of his life from chronic alcoholism and died on 25 March 1956 at age 50 following a heart attack in Beverly Hills, California. His body was cremated, and there is a plaque in Westwood Village Memorial Park Cemetery in Los Angeles in his memory. Years later his son Nicholas scattered his ashes into the English Channel in Mount’s Bay, near Lamorna in Cornwall, where his father had spent his childhood.