He was born in Canning Town, (East London since 1965). Leach was catapulted into a Criminal career by his love of West Ham United F.C. Before long, he was a member of the notorious Inter City Firm, a gang of hooligans who followed the East London club.
Leach started work as a bouncer in East London, where he became involved with Pat Tate and Tony Tucker, both of whom worked as large scale dealers in ecstasy during the rave era in the late 1980s. Pat Tate, Tony Tucker and Craig Rolfe, were murdered in December 1995, shot to death in a Range Rover on a farm track in Rettendon, in what are known as the Rettendon Triple Murders.
In 2003 Leach wrote a memoir about his Criminal exploits, entitled Muscle. In 2007 a film based on the book was released, entitled Rise of the Footsoldier and starring Ricci Harnett as Leach.
In 2015, Carlton Leach worked with Ricci Harnet to organise another movie about his life, Reign of the General but, after losing a legal battle over copyright, the film was taken over by the owners of Rise of the Footsoldier 1 and released. The same people went on to make Part 3 of the franchise in 2017. Leach claimed to have no part in this movie and commented on Twitter that it was fictional and no longer his story.