Those old enough to have lived through the Cold War will remember the constant and terrifying threat of nuclear attack.
With international tensions at a dangerously high level in the latter half of the 20th century, it is no surprise that the UK Government had plans in place to keep high-ranking members of the Government and Royal Family safe in case the worst came to pass.
Among these was the construction of a bunker buried 100 feet under Corstorphine Hill and beneath 10 foot of reinforced concrete, which was Scotland's first line of defence against the threat of a nuclear attack.