There were quite a few student clubs on Mendip the weekend that that Spreader was found, perhaps one of those is missing it and they do not realise?
Cambridge were one group staying at Upper Pitts, I believe there were also groups in at the Shepton?
(On the off-topic part, I believe the colour coding on the Wessex's part at least doesn't extend to coloured tape. As far as I am aware all of the ladders should have a red rung near the top/bottom which marks them? None of the other kit in the tackle store is marked with colours alone...)