I was also about to say, I'd treat the walls with PVA first! A 1:4
solution would be plenty strong enough; any more is a waste.

PVA is a multi-purpose adhesive; it's water soluble so just wash out
under the tap. It comes in everything from expensive little 125 ml
pots
(woodworker's glue), through 2.5 litre cans of "builder's adhesive"
at
B&Q, up to massive drums of the stuff at Jewson's.

David

Hmmm...wouldn't wallpaper paste have the same effect?

Bruce