This was WWII RAF Fighter Command Sector Operations Room and Gun Control Room. It survived the war and there were attempts preserve it as a museum and various other possible uses. But despite a petition and protests, it was demolished in 2009.
It is reported that the stone chippings between the two layers of roof (to protect against explosion of bombs) was “quarried” for use by a contractor.
Sub Brit visited in 2004 when the building was intact though some things had been removed. The site has been cleared and houses built on the site.
It was always known locally as The Black Building.