Jeff - um it was
a) Sunday
Could have been the Spit but would have been with its hurricane counterpart as BBMF....
Alternatively what you may have heard was the totally gorgeous P-51 Mustang, which was flying around loads............ and there's a couple of Mustang's based over at Seething.... I think essentially the engine is similar to the Rolls Royce 28 litre Merlin 12 cylinder, but made under licence. Think it's Packard - but not into planes that much so cannot comment........
Where in Norfolk are you?