Utterly daft to expect the CofA to be carried on all instructional flights within the UK FIR...........Daft ideas can spring from the Belgrano before their impact has been properly addressed.
Except that the requirement to carry the CoA on all flights has nothing whatever to do with the Belgrano, it is a requirement of EASA and, as such, is European law. There is nothing you, I, the Belgrano or even the UK Government can do about it.