Larwill was born in Ballarat, Victoria. He studied at Prahran College of Advanced Education and the Preston Institute of Technology, before founding Roar with Mark Schaller in 1979, originally in a studio in Green Street, Prahran before moving to Brunswick Street, Fitzroy in 1982.

Ashley Crawford,  art critic and commentator, described Roar Studios as 'a radical group of anti-intellectual, expressionist painters that became a focal point against the conceptualism (prevalent) at the time ... Dogs and beer were always welcome - it was the opposite of the art world then.'

Larwill's paintings were raucous, raw and primitivist, combining naive figures, crude patterns and detail in thick black lines and hectic colours.