shouldn't Ruth have remembered the fire at Brookfield and Grac's death?
Should she? It was well before Ruth's time, and even before Jill's Ambridge time, I think. It's only Peggy, Carol and Christine who'd really remember, and they're hardly going to have chats reminiscing about how wonderful Grace was when they're close to Jill, and often with Jill.
And although I understand Jill may also have felt she was always in Grace's shadow and having to live up to her, it's mostly something in her head - it's not like we've heard her going, "well, I couldn't live up to Grace, of course," at every family gathering (in stark contrast to her banging on endlessly about Toby,) even if she sometimes felt ithat.
I also suspect that unlike those of us outside Borsetshire, who can receive BBC Radio 4, Ruth won't ever have heard, "I must save Midnight," "Grace! Grace! " every few years - so while she's probably aware Phil's first wife died in a terrible accident, and she probably knows about Robin and Elizabeth, it's just past history to Ruth, and I don't think any of it will be top of her thoughts.