Well, second try - and still no go. And annoyingly the Autowatch support guy, who unfortnately lives in Scotland (so a long way away) has an
Ateca (not a Cupra) on which he has a fully functioning Ghost immobilser. They've tried VW files, Skoda files, SEAT files, all failed, or partially worked.
Suggestion now (from Autowatch) is to try a Ghost 2 Pro, which is dual CAN, and will cost me another (a goodwill gesture from the auto-electricians) £200. Hey ho. I hope it works. I probably wouldn't have bothered on the Cupra at all, but I had the Ghost 2 already from my S3 and thought it would be simple to transfer (as did the fitters!) Their only other suggestion if the Ghost Pro doesn't cut it is a MetaTrak system, but at £400 plus a monthly subscription of £12 is even more expensive, and given car theft in our area is pretty low, and the
Cupra Ateca not exactly high profile, I'm not sure it's worth it.
Meanwhile I have sitting on my desk a Ghost 2 immobiliser - not much of a second hand market I guess, as I expected the fitter to take it away for exchange/use elsewhere, although he did ask if I have another car to fit it to, so it's still a viable unit. Perhaps it's a registration issue. ETA: Apparently the odd one does get sold on eBay, so I can hopefully recoup a chaunk of my outlay.