I’ve only read two books by Richmal Crompton, but she seems to be interested in studying the individual members of large families. In The Old Man’s Birthday, she focuses this interest around Matthew Rowston’s 95th birthday.
Matthew has led an exciting and sometimes disreputable life, but he married an extremely conventional woman and now lives in a village stifled by class consciousness and respectability concerns. To this birthday party, he has insisted on inviting his grandson Stephen, who is living with a married woman and has been cast off by most of the rest of the family. Part of Matthew’s motivation is a perverse desire to shock these family members, but when he meets Stephen’s partner, Beatrice, he is also reminded of a girl he loved when he was young.
This novel is about how the introduction of a single person into a group can change dynamics that seem fairly set. You may feel that a multitude of difficult situations are resolved too easily, but still, this is an enjoyable and touching novel. I read it for Classics Club and was glad I did.
whatmeread 
I read this a few years ago and can’t remember much about it now, but I know I enjoyed it. I would like to read more of Richmal Crompton’s books – so far the only other one of her adult novels I’ve read is Family Roundabout.
I haven’t been able to find them very easily. I think I ordered both that I read from England.