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. His work appeared in many newspapers of the underground press, including the San Francisco Oracle, the Berkeley Tribe, the Fifth Estate and the Ann Arbor Sun.
