If for example, you were also bringing an instructor along and getting instruction towards your IMCR, you might fail that "wholly and exclusively" test.
An interesting point.
If the presence of an instructor caused the test to fail, would that not imply that the IMCR has a
value to the pilot?
And if it has a value, that opens up two things
1) An HMRC attack on the pilot under the BIK rules is now possible
2) Flight training should be allowable against income tax (obviously pro-rated according to the % of business v. total airborne time).
One accountant (who I know for sure was
not a specialist in this field) told me that CPL/IR training is allowable against income tax, if you are training to be a commercial pilot. But not for a normal non-aviation business owner. Accordingly, I never claimed any of my training costs (which to date must be of the order of £20k and that's before I am done with the ridiculous waste of time and money of the JAA IR).
I am not an accountant but I feel that HMRC cannot have their cake and eat it. The acquisition of an IMCR or an IR very significantly improves the despatch rate on business trips, and should thus be tax deductable (at least partly), and that drops a spanner in the works of disallowing a business flight on which an instructor is present.
I am sure this subject has been looked into by various people, because many if not most high-end aircraft owners are flying with a semi permanent instructor in the RHS.