Planespotting

I was walking the dog down a country lane near home this morning when all of a sudden a very loud rumble above us scared Jasper silly. Looked up to see a VERY low flying aeroplane seemingly just above our heads (probably wasn't; felt like it though). By the time I pointed and focused the camera it was on its way and I just got this rear view.

Any aircraft experts out there care to identify it for me?