From very little information 
It had a white cover and the title was something like King of the Castle.
It was about a girl called Jane (I think) and was basically a recall of her childhood. Bits I can remember are:
- She failed the 11+ because she forgot to turn the paper over and do the last question.
- A chapter about outdoor games they played including Kick the Can
Not a lot to go on I know but I'm always amazed by how many of these mysteries are solved.