Before turning to acting at the age of 24 he was a professional boxer and racing driver, making his stage debut in Ireland in 1935. Repertory theatre led to his screen debut in 1937 with an uncredited appearance in Knight Without Armour.

After the Second World War he re-appeared in a number of bit parts throughout 1947 in films like Hungry Hill and Odd Man Out, which in turn led to larger roles in movies such as Uncle Silas (1947), Easy Money (1948) and in particular Ken Annakin's Broken Journey (1948), where he played the pilot of an aeroplane that crashes in the Alps. He then graduated to leading man status in Terence Fisher's Portrait from Life (1948), as a British army officer who helps an Austrian professor track down his missing daughter. 1949 saw perhaps his best role, that of safe cracker turned spy Philippe Lodocq in Robert Hamer's The Spider and the Fly.

He was cast as a British Army major dying of tuberculosis for the film Trio (1950), but actually contracted the disease and had to be replaced by Michael Rennie. He recovered his health in less than a year, but his time away from the screen hurt his career, and he starred in less prestigious B movies such as Home to Danger (1951) and Operation Diplomat (1953), as well as the Hammer films Yesterday's Enemy and The Stranglers of Bombay (both 1959). This period also saw him play a number of Hollywood roles, such as Prince John in Ivanhoe (1952), Ned Seymour in Young Bess (1953), Caiaphas in King of Kings (1961) and Prince Grigory in Taras Bulba (1962).

One of his most famous parts was the title role in william Castle's cult horror film Mr. Sardonicus (1961), which several decades later led Director Stuart Gordon to cast him in his horror film Dolls (1987). The 1990s saw him continue in a similar vein when he appeared in five films of the Puppet Master series as Andre Toulon.

He was married to the Scottish Actress Jane Aird until her death in 1993, and then to Margret Allworthy until his death in 2003 in Ipswich, Suffolk. He is buried at Church of St Mary in Benhall.

His television credits include Thriller, Armchair Theatre, The Saint, The Avengers, The Champions, Department S, The Troubleshooters, Space: 1999, Secret Army and Kessler.