Can you help find yhis book?

[Raven08]

Very vague I'm afraid
...
I read it as a child in the early 1980s.
A group of friends growing up in post war London.
I think the girl was called Bella?
The mother had a secret ginger parking cake recipe?
I think it was it was about their adventures.

I think you mean ginger parkin.

Gemini suggests "The Baker Street Choir" (also known as "The Baker Street Choir Boys") series by Christine Pullein-Thompson

The Family From One End Street.

But that seems to be a hallucination, sorry!

Yes, I think that author was a lot earlier?

Yes! Parkin :)