Peasemarsh (full name given in the script as Mr. Harold Peasemarsh) is a slick car salesman in Five Children and It. The proprietor of Peasemarsh Automobiles ("The Name You Can Trust"), he's the only tradesman willing to take the children's gold coins, conjured by their wish to It. He sells Cyril a red Portman Speedster 3000, an 8 horse power vehicle touted in Motor-Car Monthly as the fastest auto in the world. He also encourages the children to take the vehicle for a test drive. The trip proves rather hazardous, and he tries to convince the constabulary to arrest them, only to find his gold coins vanishing.
Peasemarsh is a variation of a character in the original 1902 book, Billy Peasemarsh, a cockney horse and cart salesman. He was updated to a car dealer to keep with the new WWI time period. In the film's production notes, actor John Sessions gave his own analysis of the character:
“I had him down as a man who’d been in the army and told everyone he’d been shot in the Boer War, but actually a milk cart had gone over his foot... He's also one of these people who try to be posher than he really is. He doesn’t talk posh, of course. He’s a spiv really and he likes to come across as raffish, but actually - notwithstanding his spats and his whole Meltonian shoe polish look - he’s just waiting to be had by the kids.”