The gunnery dome at RAF Wyton is an extremely rare survival of a type of wartime RAF building which was once common; although wrecked inside at the time of the photograph (2007), the exterior was well preserved. It is believed that this is now a Listed building.
See the diagram below for how it was used for gunnery practice. The drawing was made by Frank Phillipson, by whose kind permission it is reproduced. Frank Phillipson emailed this website on 12 June 2014 to say that the Wyton gunnery dome’s: ‘outer covering of chipped stone is as it was originally specified and therefore I believe is unique amongst the surviving 40ft diameter RAF Concrete Domes.’
A similar dome is being restored at RAF Langham, see:-http://www.friendsoflanghamdome.org/index.html
Frank Phillipson also wrote: ‘You might be interested in the following link to a 1951 Pathe newsreel clip of the “Portobel” Dome (similar to the Wyton type) showing what it was like inside under training’: