Leo Murray of Monkey-Do (the people who built the tree house) had to come to the square today (Saturday 22nd) to replace the bolts that hold the climbing net to the platform.
Someone had removed all but two, making the net look from a distance like it was still in place, but actually meaning it was unsafe.
To do this would have required an allen key, a spanner and considerable strength (the nuts were nylon-lined locking nuts). It would have been a deliberate and specific act. There was no sign of the bots or nuts. They'd been taken away.
Everything is sorted now and the tree house as sound as ever.
All a bit odd. As Rapids Johnson says, "Keep 'em peeled".