Curwen was educated at Sherborne School and Sidney Sussex College, Cambridge after which he was commissioned into the 4th Queen's Own Hussars in 1948, serving in Malaya.

[2] He returned to the service's London headquarters in 1958, had another spell in Bangkok from 1961 and then two years in Kuala Lumpur.

[4] Curwen spent three years as SIS liaison officer in Washington D.C. from 1968 and was then head of station in Geneva.

[6] His tenure was notable for the successful exfiltration from Moscow of the KGB officer and British agent Oleg Gordievsky.

[4][2] His obituary in The Times noted: "He possessed a romantic patriotism that belied his hard-headed persona.