Love this thread!
I remember loads of these:
Olga da Polga
Ramona books
Rumar Godden books
Little Grey Rabbit
My dc are also voracious readers and I've had a huge nostalgic trip buying and re-reading all my childhood faves.
Not sure if it's been mentioned but....The Bullerby Children? I remember reading the whole book in Hendon Library in 1982 while my mum looked something up. Dd has a copy on her bookshelf now 
Break in the Sun - Bernard Ashley - the book from the TV series
I have a couple of very obscure ones, anyone remember these:
I think the title was All About Aldo. Short chapter book about a boy learning about animals being killed for meat and being uncomfortable about it and thinking about becoming vegetarian.
Hi There Supermouse - about 2 sisters who did dance and drama but one was much better/prettier than the other one.....
And this one no-one has ever been able to identify - I am desperate to know! It's a picture book, large, square about a little girl and this group of 12 men (Greek Gods, idols...??) think they were called January, February etc....? Does this ring any bells with anyone?