Loud bangs- sonic booms ?

[coppice]

I live 10 m north of Thirsk . I was walking on the edge of the NY Moors at 9.30 this morning and heard two deep ,loud double bangs (boom -boom, boom - boom ) from the East. Loud enough for every pheasant to start calling in alarm . Not the usual pigeon scarers /clay shoots but really quite disturbingly big bangs.No unusual aircraft activity - Hawks doing aerobatics to the west as usual and some light civilian planes. Noise sounded from a long way off and the only thing I have heard like this before is naval guns at a live firing range in NW Scotland and a sonic boom off the Welsh coast. No quarrying I can think of and planes only break sound barrier over the sea I think- and that is the best part of 40 miles east.

Anybody else hear this ? Ideas?