Penelope Wilton/Mrs Beddows - spoilers
I know this board has many fans of the original novel and the 1970s adaptation neither of which I'm familiar with, so I'm going out on a limb here but I have enjoyed this Andrew Davies adaptation.
The scene between Sarah and Mrs Beddows on the train I thought was wonderful, it was that moment when Mrs Beddows realised Sarah and Robert had been together in Manchester - slightly winded but quickly struggling to regain composure. I've read Hermione Baddeley was excellent in the 70s version (it's on my 'to watch' list), but for what it's worth I thought Penelope Wilton was marvellous.