Training for the IMC rating is permitted outside the UK provided that the flying training
is conducted by an organisation that is approved by the UK Civil Aviation Authority for
such purposes. Instruction on the course may only be given by an IRI or by an FI who is
qualified to teach applied instrument flying.
However IN 2015-009 adds a restriction to that:
4.3 In addition, the CAA will authorise instructors to instruct for the IMC Rating/IR(R) if they comply with the following:
a) the instructor must hold a Part-FCL aeroplane licence issued by the UK CAA;