Peter Firmin was the founder of Smallfilms, along with Oliver Postgate. Between them they created Ivor the Engine, The Clangers, Bagpuss and Pogle's Wood.

Most of the animating was done in a shed in Kent. He is also an illustrator, for instance he illustrated Seeing Things Oliver's autobiography. His daughter Charlotte is also an illustrator.

Peter also co-created, with Ivan Owen, British TV puppet legend Basil Brush in 1963.