Cheers, think I've (almost) got it sussed! Don't have the originals to send away, that's just a pic I stole off eBay, the old ones are lost and will no doubt turn up after I get new bolts, as is often the case!!!!!

Done a bit of digging, looks like the smaller ones are M10 x 25mm and the longer ones are M12 x either 110 or 116mm still haven't confirmed which.