Nigel remove your phone number from here unless you want to be inundated by junk calls and PM Mozzy he will be happy to help you. Just click on his name then click, Open conversation.
I have BOTH original Remote-Fob keys Marked Key 1 & 2 on their cases and a separate hard key as well.
Only Fob key 2 is recognised by the remote sensor. Key 1 is totally ignored.
The remote fobs both have nice new sets of batteries and they both display the appropriate red LED flashing rates on both initial press and hold (slow then fast flashes). All keys can mechanically open the doors and start the car.
I can't see a way to get the car to acknowledge key 1.
I thought this model/year automatically re-synched when you put a key in the ignition and it re-learned the fob if it had been dead through battery replacement. Puzzled, I am.
Success!
Connected the Nanocom with the ignition off and no key in as suggested by Wammers.
Checked the RF memory which declared it has seen valid key-codes.
Cleared the RF memory.
Wrote all settings successfully.
Now BOTH "Original" keys 1 & 2 are able to remotely lock/unlock the car. Happy Days indeed (easy to please aren't I )