Was thinking this sits under the clockwork on some DC3's, but the perspective / angle is wrong. Then figured it was the front intake for a Fiat '55, but that ain't English.
So, my guess is its a trainer of some sort...don't know why, it just looks like its from a friend of a Chippie., looks too 'agricultural and not sleek and the sort of thing you'd find attached to a fighter.
Provost ?