Right, Tried the battery trick and no joy. So I decided to dump the thing on the drive, use the GTI and get xmas out of the way before deciding on the next move.
This morning, however, I had, what is described in the trade, a "right result!". Having pondered over the problem over xmas, I bit the bullet and took it to my usual main agent. I figured they might not be too busy between xmas and the new year. Spoke to the guy i normally try to deal with and explained the story. They were actually run off their feet but he went off to speak to an engineer and agreed to quickly run it in and connect it up to at least diagnose the problem for me. Came back 15 minutes later with the diagnosis. O/S REAR SPEED SENSOR FAULTY. "How much do I owe you?" I asked. "Oh nothing" he replied. Over the moon I walked to the parts department with the reciept for the other rear I'd changed earlier, and they had another one on the shelf. Came home, 10 mins to fit it and BINGO, ALL WARNING LIGHTS OUT AND CRUISE BACK TO NORMAL.
To say i'm pleased is an understatement. This dealer consistantly gives me excellent service and an e mail will be off to Bracknell once again, to recommend them for the dealer of the year again.
Thanks for all your help. Just the Thermostat to replace now (it's the common failing, Stuck open).
Happy new year to all.
Trevor