 According to Grimshaw, his major influences were Stanley Mouse, Rick Griffin and Victor Moscoso.Grimshaw was active in the anti-war movement and was a leading figure in the White Panther Party, founded in 1968 by John Sinclair, his wife Leni Sinclair and Pun Plamondon.He was Minister of Art for the White Panther Party which modeled itself after the Black Panther Party.