(Cue manic laughter!) You, sir, are a b****y genius!
Went and got the drivers you found. Coincidentally I'd seen them and discounted them as 3Com and therefore not what was wanted, and spent fruitless hours trying to better them.
Extracted them and replaced the old drivers with them. Did Configure>>>Install new Ndiswrapper> and got the raspberry over no device present again.
So I went back through your help and advice, and did as Root:
ndiswrapper -a 0d8e:7802 net5523
modprobe -r ndiswrapper
Then unplugged and replugged. And it burst into life! See, it posts to Forums!
I will now set about testing. See if it survives Hibernation and reboots. More follows.
(Goes off chuckling and giggling. Muungwana Rules, OK!!)