Anne of Green Gables
Richmal Crompton's William books
Jacqueline Wilson (my own personal faves being Sleepovers, Candyfloss, and Bad Girls)
A Little Princess by Frances Hodgson Burnett: I first read it when I was 14, nearly 15, having seen it in WHSmith's, and correctly identified it as a book with "Anne of Green Gables appeal". When my English teacher learned I was reading ALP, she said "That's very young for you; really good stuff, but it is a book for 11-year-olds."
Tom's Midnight Garden by Philippa Pearce, and Cold Christmas by Nina Beachcroft (two very similar books; the latter is, sadly, out-of-print and under-rated).