Barnton Quarry derives its name from the stone workings found at the Corstorphine Hill in Edinburgh, where stone was extracted up until around 1914. During World War 2 the RAF built a Fighter Command Operations Room within the quarry to operate for Turnhouse Sector of RAF Fighter Command. RAF Turnhouse now being Edinburgh Airport.
In the years following World War Two a second structure was building within the quarry grounds. This was the underground R4 bunker, which was a three-level bunker built in 1952 and given the code letters MHA. This operated as the Sector Operations Centre for the Caledonian Sector, receiving information from radar stations across Scotland. The ROTOR programme was changed under the 1958 plan and the system made largely redundant. Due to the time delay involved in passing information from radar station, to the SOC, and back to the station from where fighter aricraft would be scrambled from were too great in the jet age. Potentially hostile aircraft would be able to penetrate the air defences before fighters could intercept them. With the development of the long-range GCI (Ground Control of Interception) Type 80 radar meant that early warning and also control of fighter aircraft could be handled from a single radar installation. Consequently, the whole ROTOR air defence system became obsolete and all the Sector Operations Centres were no longer required. Barnton Quarry was closed as a ROTOR R4 bunker.
During the 1960s the four R4s constructed found new uses as Government Regional Bunkers and Barnton Quarry became a Regional Seat of Government. Although a supposedly secret government building, the existence of the nuclear shelter was made public on Good Friday, 1963, when a group known as Spies for Peace revealed details of fourteen RSGs throughout the country. Barnton Quarry remained an open secret in the Edinburgh area and CND even made protests outside the entrance to the site.
Lothian Regional Council inherited Barnton Quarry in 1984, selling the property in June 1987 for £55,000 to a Glasgow developer. The site was put on the market again in August 1992 but before it could be sold the interior was largely destroyed by fire. Since this has released asbestos fibres throughout the underground rooms and an extreme state of dereliction existed. The site was purchased by James Mitchell, Managing Director of Scotland’s Secret Bunker. Since 2011, a team of volunteers has helped with renovation efforts. The aim is to create a museum and education centre with a view to restoring the R4 bunker to the original 1952 configuration. Updates can be found on their Facebook Page; Barnton Quarry Restoration Project.