Thanks Preee, I knew there was something about the key but couldn't find it in the manual. Had it towed to the Ford dealer this morning but they can't look at it until Wednesday. God knows how much it's going to cost - £60 just for a diagnostic and another £50 for the tow so far.
Yes it has, the factory fitted one. Basically, it does nothing when you press the start button. Radio works, lights work etc but it doesn't start the engine at all. The odd thing is, 5 minutes before it was fine. It was just when we tried to start it to head off for Xmas dinner!
Doh! just read that again - I don't think it was flashing but I'll let you know. UPDATE - no flashing. Although my thoughts are it is immobilised somehow!