Examinations conducted in UK by UK Examiner may not be recognised by another state so I assume that the opposite is true
However the flip side is also true - Examinations conducted for foreign state pilots by UK JAR Examiners may well be recognised by that foreign state (JUST NEED TO CHECK FIRST)
As JAR licenses were issued to the same common standards then I can't see why the test in Switzerland for UK IMC rating reval would not be OK. In fact if the Examiner has IR priveliges then that should be more than sufficient.
May be hard for some to get their heads around though