Obsessed with finding a book

I wonder if anyone can assist. I am really trying hard to find a book which I read many times when I was a teenager. Also re' read it as a young woman in the 70's and 80's. The problem us that I cannot recall the title and was hoping someone would recognise the book if I detail some of the characters' names and brief details of the plot. I seem to becoming obsessed with finding this book - oh dear it must be because of lockdown. Anyway - briefly some of the characters are Monica, Geraldine, Phillip and Greta. The first three are unrelated children staying in a vicarage whilst their separate parents are away. Greta is the governess at the vicarage. The story follows the lives of the children as they grow up. I think the story must have been written late 1940s and a woman author. I would be so grateful if anyone could come up with the title and/or author. There are websites which purport help with searching for books but no help in this case.