His greatest success came as the naive and nervous medical student Michael Upton in the popular TV series "Doctor in the House" (LWT, 1969-70) and its successor "Doctor at Large" (1971). His youthful good looks and sweet confusion drew an enthusiastic and not wholly maternal response from female viewers, and Evans found himself typecast by his talent for comic anxiety and sexual vulnerability. Serious roles eluded him, and he declined to make a third "Doctor" series in 1971, only to return to type as the perky but put-upon young English teacher Jeremy Brown in the London Weekend Television comedy series "Mind Your Language" (1977-81).
During his hiatus from television, he starred in his last film, the dismal "Adventures of a Taxi Driver" (1975). He concentrated for a while on theater work, which included directing plays at Theatre Clwyd in Mold, but a period of debt and dependence on Social Security drove him back to TV and the all too familiar role. As his fresh-faced looks faded, he found himself less in demand and left show business. In a classic example of life imitating art, he had been working as a taxi driver for several years at the time of his death.