Purvis had dwarfism, and at 4 feet 2 inches (1.27 m)[1] was mainly cast in roles requiring actors of short stature.

He appeared in three of director Terry Gilliam's early fantasy films, with significant roles in Time Bandits and The Adventures of Baron Munchausen.

For twenty years until 1991, Purvis performed as part of a musical comedy double-act with Kenny Baker, billed as the "Mini-Tones".

At that time the duo had reached the final on the talent show Opportunity Knocks, and were reluctant to put the Mini-Tones work on hold.

[2] This and the 1990 death of David Rappaport led to Terry Gilliam's indefinitely shelving an intended sequel to Time Bandits, where both actors played titular roles.