"Listen right. We're lookin' for a lad who can do his stuff. I've heard you're a bit tasty, no messin' around or you'll get a slap. Remember, I'm the monkey, and you're the cheese grater. So no messin' around."
Harold is in charge of the criminal Cartwright Gang and seems to have made his name and fortune in bars, pubs and pool halls, but is nonetheless not a significant player in the London criminal underworld. Cartwright is the first person to provide the protagonist with jobs. He claims to be confrontational and that he fears no one but it is later revealed that he is a coward and is afraid of Albert and Archie Crisp.
"Listen right. We heard you're a boy who can do his stuff. And by hookers and by crooks. You've proved you ain't bad! Yeah! Ain't bad at all, sunshine. You know what I mean?"
―Harold Cartwright in 1961.
He hires the protagonist to help him in jobs which he gets from the Crisp twins. His missions include wiping out two small-time gangs under the orders of Mr. Caukenbolls, by blowing their hideouts up and killing their members in a shoot-out, chauffering Caukenbolls and defending him from rival gangsters, then rescuing him from them. After those events, the rival thugs are wiped out and Mr C. is taken to a safe place. Soon later, Harold tells the protagonist to try and discredit Gene White, but at the end, the player kills him and recruits his girls. Harold and the protagonist then apparently had sex with the prostitutes and it was recorded, so the protagonist has to destroy trucks filled with the tapes. Next time, he asks the player to murder Poundage Fern and act as him in a car race in order to get the cup. First, the player murders his bodyguards, then Fern, and wins the race. A bit later, the protagonist steals a Jug Swinger, apparently for Harold's mother. However, it's Endeavour Chambers' car, and the government takes the player as him. This leads to the protagonist to cross Hans Nemesis' actions for the first time. Another time, he tasks the player with delivering dolls for his little cousin, Ashley. The last job for him involves killing a guy who is blackmailing Harold. His son is killed as well. After that, the player meets Harold personally, congratulating him on how well he has done.