Flying overhead Cranfield a very common experience is I report my level and routing (via the beacon), and they ask if I am VFR or IFR. In the usual UK 'IFR exists only in your own head OCAS' situation, I am usually IFR, I.e. I have chosen a level consistent with my heading IFR and am above MSA so I can be IFR if I want.
They don't want me IFR because they will then have to deconfiict me from the IFR training traffic so they usually request I overfly them VFR. If I am in VMC I comply but it does make a bit of a nonsense of the idea of procedural deconfliction...