Not so:
E3.1 UK IMC RATING GENERAL INFORMATION
The IMC Rating is a national rating and can only be
endorsed onto a UK or JAR-FCL aeroplane licence.
So, any UK-issued pilot licence (except NPPL) may include an IMC Rating.
Additionally:
The privileges of the IMC Rating may be
exercised in UK territorial airspace. The IMC Rating may
not be used in the airspace of any other Country unless
permission to do so has been given by the appropriate
authority of that Country.