If anyone else has this problem with their clio immobiliser and comes across this threat DO NOT despair. My 13 yr old clio did not have to go to the scrapyard.
I had the immobiliser removed from the car and that plus the 2 keys were sent to Autotronics: first class post on the Monday and returned and fitted to the car by lunch time Thursday. Given the car had been off the road for a couple of weeks this was of only minor inconvenience and at what I considered to be a reasonable price: less than £100.
Hope this helps someone else.
Jan S
March 2014