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
I passed by Cranfield the other day and gave them my estimate and level for the CIT, which happened to be directly on my route, which might have made me sound like IFR traffic. They seemed quite keen to make it clear that they were treating me as VFR - didn't bother me one way or the other!