In reply to IainWhitehouse:
Not sure if the sizing on these is the same as the old Cliff Blues? Anyway, I've used Sportiva's a lot (they fit my feet bettter than 'owt else), and for sizing:
My street shoe size 43
Muiras 39.5 (v.tight)would never do this to my feet these days tbh
Barracuda 40 (tight) 41 (thin sock, mtn routes)
Katana 40 (v.tight) 40.5 (tight)
Cliff Blues 41 (thin sock)
Nepal Extremes 43.5
Go figure!