Stirling was the founder. He needed a 2IC. The then Captain Mayne was in jail, awaiting trial on a charge of punching a colonel and chasing him with a knife. Stirling made Mayne an offer - I can get you out of here, but you then come and work for me.
Mayne did, and spent the rest of the war killing Nazzies left right and centre. The only british servicemen ever to be awarded 4 x DSO's. He was an international rugby player, a decent boxer, and liked a fight and a drink in equal measure. The war came along at just the right time for him to have a fight whenever the mood took him.
Read the link - he really did kick some serious Nazzie butt.