In the 1950s, he played the time-traveller (also known as "the voice") in the British sci-fi radio series Journey Into Space. Guyler then took on the role in the title character of a Scotland Yard detective in the Light Programme series Inspector Scott Investigates, created by John P. Wynn, that ran from 1957 to 1963. During the half hour programme a crime was committed; Scott and his sidekick, Det. Sgt. Bingham (Brian Hayes, brother of Patricia Hayes) interviewed two or three suspects; then, while music played, there was a short intermission for listeners to guess 'whodunit' before the final reveal. In Henry Reed's series of radio dramas about Herbert Reeve's inquiries into the life of Richard Shewin, Guyler played General Gland, soldier-scholar, campanologist and author of war memoirs, most notably in Not a Drum was Heard. During the 1960s and 1970s, when he starred in the satirical radio programme about life in the British civil Service The Men from the Ministry with Richard Murdoch, Guyler played the pompous, self-important Number One in the General Assistance Department, with Murdoch as his diffident but equally incompetent Number Two.