Wingfield was born in Cardiff and grew up in the Grangetown community, a good student who enjoyed athletics, music, outdoor activities, and drama. At the age of fifteen he was the Welsh National Trampoline champion. After his A-levels he entered Brasenose College, Oxford, and in 1982 began medical training at the prestigious St Bartholomew's Hospital in London.

His time, however, was not devoted solely to medicine. In 1980 he spent his summer break at the National Youth Theatre of Wales where he discovered the sense of camaraderie and belonging that characterise truly outstanding acting troupes. His four-week stint with this youth theatre changed him in ways he didn’t fully appreciate at the time, but which were to have a lasting impact. He also worked during his college years at the Brasenose Little Theatre, both performing in, and producing, a variety of plays.

Shortly before completing his fifth and final year at St Bartholomew’s in 1987, Wingfield realised that the practice of modern medicine was not for him. He’d gone into medical school with an idealistic view of doctors as altruistic caregivers. The reality of hospital life, and the far-too-often selfish approach of some doctors to their work, both disillusioned and saddened him. One month before he was due to graduate, he made the decision to leave medical school and pursue acting as a full-time career.

Wingfield began his formal acting training at the Guildhall School of Music and Drama in London, coincidentally located just across the street from St Bart’s Hospital in London. His training covered the range of an actor’s repertoire, including voice, movement, and the acting skills necessary to be successful in arenas ranging from radio to mime. Peter was chosen in 1990 to compete for the BBC’s Carleton Hobbs Award for radio, which he won.

In 1990, shortly after leaving drama school, he landed his first television acting part as a taxi driver in the film Antonia and Jane. The qualification that led to his selection for the part was that he knew how to drive.

Wingfield appeared regularly on British television, and starred in numerous productions. His last major role in British television was as Tom Kirby in the series Noah’s Ark in 1997. Portraying a vet in the series, Wingfield had to take medication to combat his animal allergies. One positive outcome of this short-lived series is that the constant exposure to animals has apparently reduced his allergic reactions.

In the late 1990s Peter played Simon Pemberton in BBC Radio 4's serial The Archers.