The latest issue of the Radio Times has an article asking people to help find the real Chummy. Jennifer Worth's daughters say she was a real person, but that Worth didn't use her real name. They say they've seen photos of her that they no longer have.
In the book, Worth says that her father was governor of Rajasthan - but according to the RT governors of Rajasthan have all been Indian. She also says that Chummy won St Thomas's Nightingale Prize three times - but St Thomas has no such prize.
So Worth obviously changed or invented a few details, but the RT is asking people to write in if they have any idea who she might have been. It's piqued my curiosity (and we all love Chummy, don't we?) so I thought I'd pass it on to see if anybody else has any ideas.
I don't read that article in the RT as the sisters saying that there's no truth in it at all - more they are saying they don't know who it was that Chummy and Sister Monica Joan were based on. They do say two sisters might have been the basis for Sister Monica Joan.
I would think that it's fair enough to change details - I could be wrong, too, but I think Jennifer Worth fictionalizes the first book far more. It's much more a 'story' based on her experiences, and she uses the notes at the back to tell you what midwifery terms mean. Whereas the last book, where she's talking about her own cancer and about death in general, sounds much more personal. I think by then she knew she'd got an audience, she didn't have to try to tell a pretty story to get a publisher, and she just wanted to say her piece.
Btw, if I'm remembering rightly, my cousin thought about joining that community in the 1950s. She ended up with a closed order (St John the Evangelist) instead ... I wish I'd asked her more about how she chose it all before she died - the whole series is making me fascinated with this.