Thanks, those are really helpful suggestions, which I’d not thought of. As it happens, I’ve just found it!! Went out with a mate to put up some ‘Lost my Favourite Toy’ posters. Near the start of the trail, just past a rooty bit, saw something glinting in the low evening sun. About a foot to the side of the trail, nestled in the ivy, but pretty much in full view there it was. Two of us had re-ridden the trail twice on Sunday, and not seen it. My piece of inner tube has now been uprated to two pieces, and my phone number is going on it somewhere. I’m going to customise the startup screen if possible on that model.