I would recomend anything by Alan Garner, especialy:
The Weirdstone of Brisingamen
The Moon of Gomrath
The Owl Service
All written between the mid 60's and early 70's.
Also, The Dark is Rising sequence by Susan Cooper published between 65 and 77.
And last but by no means least, The Driftway by Penelope Lively written in 1972.
I know these are all pretty old books but I loved them as a kid and I'm only 36 now. I suppose it depends on whether your son can get passed children that talk the queens english and a distinct lack of technology