I have no idea if this will work and I'm sure it wasn't worth the effort but it seemed like a good idea at the time (which was several weeks ago) mainly because it's such a rare thing for the squirrels to leave hazelnuts long enough for them to ripen and fall off the tree.
I picked up all this lot and spent an age shelling them - lots were hollow
Then layered them in a jar with salt, something I have plenty of due to buying a gi-normous bag full from Approved Food about 5 years ago.
The instructions came from the book I picked up at the book sale 'How to store your garden produce' by Piers Warren.
I'll keep them for a while to see what happens - edible or mouldy?