There were two particular examples here. Anne Reid (known from a long way back as Ken Barlow's first wife in Coronation St) played the downtrodden mother of the title. Downtrodden was written all over her face, and all Anne had to do, in a sense, was play to that look on her face, and she'd express everything the director and scriptwriter wanted. (She does do a lot more, but that doesn't negate my point.)
Steven Mackintosh also appeared. Mackintosh is unlikely to play a trustworthy character; there's something about the shape of his face and the ways his eyes look at you that tells the audience: if you're suspicious of this bloke, you have every reason to be. In his role as the Mother's son, he was playing an ordinary ambitious family man - but you could see there was something sneaky going on. Mackintosh didn't need to do anything in particular to convey this; it's written in his face. (I don't know what Mackintosh is like in real life - he's probably a delightful person - but his face, on screen, says something different.) I couldn't remember where I'd seen this actor before, and of course IMDB was its usual helpful self and reminded me that Mackintosh had been the villain in one of the Prime Suspect episodes. He'd played a man who had cut himself off from emotions, who had no qualms about his villainy or his control of weaker people, and who seemed able to bring even the imperious Helen Mirren to her knees. Mackintosh played this role brilliantly...his face helping not a little.
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So what was the point of this unpleasant exercise? Does seeing it encourage us to want to be kinder to our ageing parents? Perhaps, except that the parent in this piece finishes up not worrying about whether her children care about her any more. It certainly shows that selfish children are a menace to older people (especially when their own children are just as selfish), but the writer of the script hints more than once that the Mother was selfish herself from way back. We never quite know whether this was because she was controlled by her husband, who cut her off from friends and other relationships (and that would seem to be the obvious reason) or whether she was just naturally not cut out to be a mother. Her behaviour towards her own daughter's lover can be seen on one hand as a natural need to be loved by someone - anyone; or it can be seen as a bizarre kind of continuation of hurting her daughter. That's assuming that what the daughter says about her mother is true, and this aspect of their relationship never quite makes sense.
An open-ended piece and thought-provoking. You would probably not want to know any of these people (you'd be likely to come out of it worse off), but perhaps they teach us something, if we're willing to stop and think about it.