Spoke to MS last night, and apparently they had shipped the UK copies of RC1 to registered testers, and they plan to then ship the RTM version and skip RC2 completely.
As far as I can see, it is a complete scam: UK testers pay £20 for a copy of RC1 over a month after it first became available, and then the RTM copy, while the rest of the world pays less, and gets all the versions.
If I hadn't been chasing them up, MS wouldn't have told me what was happenning, so I dunno how many people are out there sitting wondering if their copy has been lost in the post.