From the radial engine I'd suggest a DH 60 Genet Moth - which had an Armstrong Siddeley Genet engine. Only 6 were built so this is a rare Moth, and I suspect a pretty rare photo. All 6 were used by the RAF Central Flying School - I think for display purposes although other, wiser Pruners may know better! All had serial numbers starting with J88**. What appears to be an RAF roundel on the fuselage is a further clue.