Never under-estimate the seductive powers of a bit of fur tied to a stick.
James leapt impulsively out of his hidey-hole this morning onto the armchair in pursuit of the creeping 'mouse' and took about 30 seconds before realising what he'd done and retiring, alarmed by his own temerity. But he'd been out in the open, with an astonished Scooter about two feet away, and nothing catastrophic occurred. Who knows, maybe he'll risk it again soon. I was able to see how big he is - almost the same size as Scooter; they would make a lovely couple of chums.
For those of you who worried, he's not up for rehoming, really. At the moment, he's still on loan from Karen, who hasn't had the time to spend with him that he needs; the deal is, that if it works out well here, I'll adopt him. If WW3 broke out amongst them all, and persisted, I would think again, but so far, so good, and I have time, patience and only occasional moments of despair, probably sitting room litter-tray-induced.