Rough Diamond is an English television series that revolves around the adventures and misadventures of an aging but still brilliant mastermind thief. The series opens as a new crop of guests is being delivered on their first day of an all-expenses paid sojourn as a guest of Her Majesty’s Government, to HM Prison, Barton.

Phil (Stephen Wight), one of the prisoners, is young and naïve, an habitual penny-ante thief, who’s trying to ingratiate himself among the prison population, inmates and guards alike. What the inmates and staff see is Phil’s lack of street sense. Des (David Jason) appears to be somewhat handicapped, a “tea boy” who is making his rounds with the tea he’s preparing for the staff of the prison. Tea Boy is seen by all as too slow to do much more than that; one guard calls him the “Stephen Hawking of brewing up.”

Des wears an ever-present, cowardly, vacant smile, with equally vacant eyes behind thick glasses. He limps, stammers and stutters. He, too, seems to nurture getting along with staff and prisoners alike, except his appears to be a basic survival skill. Another apparent survival skill he seems to have learned is currying favor with the guards, an example of which we see when he suggests to one of the guards that he should search the cell of the new kid, Phil. Turns out what they find is a key that Des has planted for them.

The search of Phil’s cell takes place as the rest of the prison population is gathered to watch a boxing match set up by Benny (Gary Whelan), one of the prisoners and the de facto prison boss. Benny has duped Phil into being there with the promise of a job for him; in actuality Phil is to be Benny’s punching bag. As he prepares for the fight, the trainer whispers to Phil that he doesn’t have to do this. Phil asks what his options are. The trainer, another inmate, tells Phil he can either be a punching bag for Benny, or he’ll be “a punch bag for the entire prison, then given over to the 'sausage jockeys,'” already leering in anticipation. Dim or not, Phil immediately grasps the wisdom of being Benny’s punching bag.

Afterwards, for the incident with the key, the warden sends Phil to solitary, a situation which Des engineers to get shortened. He also suggests, without actually suggesting it, that perhaps Phil being bunked with a more compliant, less troublesome prisoner might change his attitude. Des is visibly horrified when the warden says that it’s a good idea, and assigns Phil as Des’s bunkmate.