Damian Harris Cycles in Cardiff has it in one of their cabinets. I was in the shop this morning and I enquired about it. They had to ask Damian (the owner) how much he wanted for it.
Alex from the shop has since called me back to say that he wants "50 to 60 quid" for it, which seems like a really good price. It doesn't have the bottom bracket to go with it, but NOS chainsets like this usually go for double this regardless..
It was fitted to a bike which they had, but was removed before it was ever used, so it's not technically "new old stock", but it's about as close as you can get and it's in perfect condition.
The shop's number is 029 2052 9955
if anyone wants it. I'm sure they'll be able to pop it in a box and post it
UPDATE - The chainset has now been sold. Apparently their phone had been ringing off the hook