Simply Paul: The simple answer is the footpath has been moved! Take a look at streetmap and you'll see it passes to the north of the tower - with the new fence, it now passes a couple of metres to the south. Nipped in through the gate, found the cache quite some way from where I left it, and whipped it away. I found a new spot for it almost 500ft away, and as I've replaced the log and the container, I'll reset it as a new cache. Thus this one is archived. Thanks to everyone who came and found it, and sorry to those who looked, but DNF'd it.
SP