On 12 December 1966 the Krays helped frank Mitchell, "the Mad Axeman", to escape from Dartmoor Prison. Ronnie had gotten to know Mitchell while they served time together in Wandsworth jail. Mitchell felt the powers ought to audit his case for parole, so Ronnie felt he would be helping him out by getting him out of Dartmoor, highlighting his case in the media and compelling the powers to act.

When Mitchell was out of Dartmoor, the Krays held him at a companion's level in Barking Road, East Ham. As a huge man with a mental issue, he was hard to control. He vanished, however, the Krays were vindicated of his homicide. Freddie Foreman, a previous individual from the Firm, guaranteed in his collection of memoirs Respect that Mitchell was shot