Looking for a lost children's book! Can't remember the title or author...

My Mum is looking for a children's book she had when she was young but can't remember the title or the author of. She thinks the book was probably published between about 1920 and 1965. It's about a family with lots of children who move to a new house in the countryside. The chapters of the book focus on each child in turn as they choose a special place around the house to call their own. One of the children chooses a room in the house which is considered cheating. The parents didn't feature much in the story. She thinks it might have been translated into English, and was probably a female author. She describes the tone of the book as quite gentle, rather than a mystery or detective story. Similar tone/era to the Wouldbegoods by E. Nesbit and The Four-Story Mistake by Elizabeth Enright.

Niche, but it would have been in the Newcastle Under Lyme mobile library in 1964-5.

I know it's not a lot to go on, but my Mum's been looking for this book for the last sixty years, and I know how delighted she would be to read it again!