After a six-year interruption for military service in the Second World War, his acting career did not reach the heights of his early years.

[2][3][5] In 1930 Fox left drama school and won a role in London's West End performing in an eight-month run of W. Somerset Maugham's new play The Breadwinner at the Vaudeville Theatre.

Following this success Fox co-founded an acting troupe, based in the West Country, where they converted a former swimming baths in Teignmouth into a theatre.

He staged the thriller Rope and following a glowing review from actor Cyril Maude, the play had an eight-week sold-out run.

[6] Fox went on to perform in J.B. Priestley's play Dangerous Corner, directed by Tyrone Guthrie; he was billed as "a great discovery".

[2][3] In 1939 Fox and Hillard were living in Dolphin Square, where they became annoyed by their neighbour Unity Mitford's habit of playing loud Nazi marching songs.

[2][3][5] After the war he continued to hold a reserve commission as a captain and honorary major until 1961, when he reached the age limit for service.

[8] After demobilisation Fox was considered too old to take on juvenile roles, and given that he had no experience as a lead actor, directors were wary of casting him in these parts.

It was whilst in Baghdad that he decided to start the Reunion Theatre; this association was designed to help demobilised actors who had been out of the business for several years.

His film credits included roles in The Lavender Hill Mob (1951), The Secret Partner (1961), The Queen's Guards (1961), She Always Gets Their Man (1962), Ransom (1974), Omen III: The Final Conflict (1981) and Mata Hari (1985).

These activities led to his devoting less time to acting—though he continued to perform, notably in television shows such as The Duchess of Duke Street, When the Boat Comes In and Yes, Prime Minister.