Rickman, I'm in Scotland where we don't have a Year R, they are still in nursery and don't (officially) learn to read and write until they are in Primary One (equivalent to year one, but the cut-off dates are different). Dd1 was quite old in her year, and learnt to read/write whilst still in nursery. Dd2 is young in her year and didn't start learning to read and write until she was in Primary one. In nursery she knew her letters and numbers but we didn't start her on reading (I was her nursery teacher!). But she is a very bright child who has now just finished P2 but is working at P3 level.
Personally I don't think many children are ready/receptive to reading and writing at reception age. I doubt very much it has anything to do with what you did/didn't do and much more to do with his age/motivation/maturity etc.