Nope, FAA IR can be done anywhere in the world as long as you can find an FAA examiner or DPE. That is usually the problem, prior to 2005 DPE's did visit the UK by invitation to conduct tests but the canditate had to pay all costs plus a huge test fee ontop.
It's not worth the hassle anymore, just bite the bullet and go to the States. I managed the Multi IR in 3 weeks, just...