Maurice Guy Smallman Bevan was born in 1921, the son, grandson and great-grandson of Anglican clergymen. His brother Roger founded the Bevan family choir, which toured widely and recorded with many of his 14 children between the 1950s and 1970s. Maurice was educated at Magdalen College, Oxford, but was soon called up to join the army. He became a vicar choral at St. Paul's Cathedral Choir in the late 1940s, where he met Deller.

Bevan was an integral member of the Deller Consort, which inevitably changed over the years; Alfred Deller died in 1979 and was succeeded by his son, Mark, who had been a member since 1964.

A Washington Post review of the Consort in October 1982 said, "Amazingly, baritone Maurice Bevan goes on and on, his voice, if anything, more resonant and more flexible than ever, but still projected with the familiar ease and gentleness."

Bevan gradually retired during the latter part of that decade, but continued to be a substitute singer at St. Paul's Cathedral well into his seventies, according to the Telegraph. He also became a regular tutor and mentor at Deller's summer school, the Deller Academy, at Lacoste in Provence. Bevan was also a musicologist and edited several important early works, including Handel's oratorio Esther.

The paper notes that Bevan was a good cook, a lover of fine wines and an avid reader, particularly of biographies.