Thanks again for all the posts which confirmed my suspicions. I did a test last night on 2 of the many papers. One pack of Kodak Bromesko 2, which is lovely, is fine but there were only 2 small sheets, one I used for a test the other was ok. One small pack of Ilford MG II is fogged. There's loads to go through and to be honest, Im quite excited at the prospect. I think Ive been given a trasure chest of goodies.
Quite a few of the boxes are unopended and I wont open them until I plan on using them. I'll continue to test the opened packets/boxes.

Storage - My darkroom is quite small, 5 x 5 metres. Ive got a book case which I use for dry materials etc but Im concerned about keeping the papers in the darkroom.
Ive never needed to be concerned about long term storage because I normally keep a few packs of paper in the fridge until I need it, but now that I have so much precious paper, Im looking at long term storage.
Presumably keeping the papers the darkroom is not a good idea due to fumes. I was thinking of a dark plastic storage box which has a lid, would that be ok to keep in the darkroom on a shelf if I keep the lid closed?
Many thanks again.