Just a point though, Silverston has an active airfield in it's midst so....
There doesn't appear to be a NOTAM out for Silverstone today or until the end of the month so it is unlikely anyone, civil or military, would be aware of any unusual activity. Silverstone is listed as a Heliport and does not appear to attract any sort of ATZ so overflight is quite legal. Likely just to be aircraft routeing through the area.