Buzzard or no buzzard

Today from Pick Up hide i'd been watching the resident kestrel pair hanging in the wind and putting on a good display then another bird appeared doing the exact same thing he was motionless in the air a more rounded shape than the kestrels and slightly larger but not much-was it a crow? Big black hanging in the air? Well no when crows mobbed it you could see the much more rounded wings and different head shape but the size was pretty much the same. Then he stopped hanging and glided towards me in the hide and Id swear it was a buzzard only it was far too small. No it wasn't a sparrowhawk either I'm well familiar with them. So any one got any suggestions A crow sized buzzard who hangs almost hovers like a kestrel.