Bobby Ball as George Mole
Who Is He? Adrian and Bretts father (although The Prostrate Years implies that Adrian may not be his child). More or less just the grumpy old man with his annoyance at the world changing around him being played for laughs. The Prostrate Years adds a new dimension to this with his annoyance at his lack of independence after becoming wheelchair-bound thanks to a stroke, providing more jokes.
Why Bobby Ball? As mentioned, George provides the meat of the comic relief (particularly in The Prostrate Years where he and Pauline are more prominent) and Balls comic timing is excellent. As well as that, hes a decent comedic actor and can work wonders with a good script. And even though hes a comedian first and an actor second, I just have a hunch that he can pull off the more dramatic moments such as his conversation with Adrian after the revelation that Pauline rejected him for the first year of his life and that George left work to look after him.
Alison Steadman as Pauline Mole
Who Is She? Adrians long-suffering mother. A serial adulterer and ardent follower of Germaine Greer but still a devoted mother. She constantly seeks to validate her life in some way including appearing on The Jeremy Kyle Show and writing a misery memoir titled 'A Girl Called S**t' that is completely fictitious. She proves to be a pillar of strength to Adrian after he is diagnosed with cancer.
Why Alison Steadman? This is a repeat casting from The Cappuccino Years adaptation but I just didnt think anybody else really suited the part. Sue Holderness (Only Fools And Horses) was a choice at one time but I just felt she was lacking something that would make a good Pauline. As well as having previously played the role and knowing the character well, Paulines role is considerably more serious in The Prostrate Years which would give Steadman a good opportunity to play a dramatic role as shes more known for comedic roles these days.