He is described as looking like a pirate, he is a year older than John and also his second in command. He is described as being much more rational and understanding, but prefers to take orders from John. He uses a machete and wears a bandanna and shorts, with heavy boots.
Carl is first introduced during The Fear when he tries to raid Westminster Palace and is sent running by DogNut's group.
When the Buckingham Palace crew come to take over St James's Park in The Enemy, Just John and the rest of the squatters confront them. When Just John is hit down by Akkie, Carl is assumed to be the new leader and tries to negotiate. The situation gets out of hand when Pod and his crew start chanting and a fight between the two gangs break out, resulting in Freak's death at the hands of Just John's three pronged knife-spear. Just John is taken as a hostage and later Carl arrives with a group of Squatters to get him back. It is decided Akkie and Just John will fight to resolve the conflict. Akkie wins and the Squatters are put under David's control temporarily.
During The End, Carl and Just John leave David's army and invade Buckingham Palace to seize control. They succeed in taking over the palace, but Just John is killed. Carl is assumed to be in charge although the books do not state what happens after.