[5] Colleano's first important role came with the popular wartime drama The Way to the Stars (also known as Johnny in the Clouds, 1945), playing an American airman.

Colleano played an Italian in One Night with You (1948), and was in Good-Time Girl (1948) and Sleeping Car to Trieste (1948) and "Broken Journey" (1948).

He worked regularly in radio, appearing in a revue Navy Mixture,[6] and had a lead part in Once a Jolly Swagman (1949).

Colleano's reputation shot up when cast in the role of Stanley Kowalski in the original English stage production of A Streetcar Named Desire (1949) at the Aldwych Theatre, London, directed by Laurence Olivier and co-starring Vivien Leigh.

Colleano had good support roles in the oddball Shakespeare derivation Joe MacBeth (1955) and Stars in Your Eyes (1956).

Colleano died in 1958 at the age of 34, when he crashed his sports car (a Jaguar XK140) in Birkenhead shortly after leaving the Queensway Tunnel.

[11] He was driving back from Liverpool's New Shakespeare Theatre, where he had been appearing in a stage production of Will Success Spoil Rock Hunter?.