It rather depends on his reading age. Is it as per chronological age, advanced or behind a bit. Almost impossible to recommend without knowing. The 'Jennings' series is fun and has been updated. I was certainly reading it at 8 and loving it, as I did the Billy Bunter books. I'm female and certainly wasn't at boarding school - a lot too much is made of similarity to lived lives.
I taught for just 1 year at a pre-prep school (the 8-9 yr. olds) and read 'The Gauntlet' to them, Ronald Welsh (historical fantasy), they loved it to a child and 1 boy developed a love of history which led him to study it at Uni.. Hope this helps.