Railings you also don't want him aiming too low. DS's best friend had a firmed offer for Environmental Science at Leeds last year, ABB. He got BBC and was turned down by Leeds, but managed to get a place at Liverpool in clearing, which had a standard offer of ABB, so he was 2 points under. Turned out to be the best thing for him as there are modules unique to Liverpool which turned out to be his favourites.
Has he or you looked for his course in Clearing? Would you like to share which course he is considering?
Can't remember whether I have said this to you, but it is useful to look at discoveruni.gov.uk to find the actual grades people on the course had.