The thread that Sanner mentions me in is reasonably informative.!
The number of each UK relates to your order number/place in the queue. So from my correspondence from Renault directly, I was told I'd be getting number 023. (In fact I ended up with No. 022, no reason given.. and I wasn't bothered do didn't question it)
The OP could try contacting the original owner of the car on the off chance they might recall their order number. Good luck with that.
Trivia:
This order number process was sold used for ph1 Clio v6's. Some orders were cancelled, so although there were 500 orders allowed for, only 256 UK cars were made, meaning there are big gaps in the numbering of the cars. Basically, any car numbered over #500 in the UK will be an import.
A system that seems to have been now dropped.