Anything which uses RF and is used in an aeroplane must be licensed unless it has a specific exemption for such use.
So whether you use a hand-held transceiver, cellphone, blue tooth fashion toy or even you car key fob in an aeroplane, it would require a licence irrespective of whether or not it is licence exempt elsewhere.
Anyway, I've had enough of this. So tomorrow I will be writing both to Ofcom and the CAA to obtain a clear statement which even the most ridiculous barrack room lawyer will be able to understand.