Www.elevenplusforum is a great (albeit intense) source for grammar school questions, and st olaves stuff can be found in the 'Bromley and bexley' section. DS is in Y7 at St O, and we just had the one past paper we bought at their open day. I think they might have specimen questions on their website, and it is a new format for the first time this year I believe. For DS I used a lot of Manchester Grammar past papers: think of a similar difficulty, and they generously had quite a few on their website 2 years ago. Good luck!