Yes can be done, there are various year intakes, year 5 etc for the Dulwich Private Schools. there will be an entrance exam and an "interview" type face to face meeting - I assume that this info is available on the school website The issue will be that he will mostly be up against pupils from other private schools trying to transfer to Dulwich schools, so his schooling to that date needs to be good enough to match those other children, or have sufficient tutoring before the entrance exam. You could ask the private schools what proportion of the children coming in at a later stage are from state schools to give you an idea. I'd have thought it might be quite low. My experience is Alleyns.