6. Many tube stations were used as air-raid shelters during the Second
World War, but the Central Line was even converted into a fighter
aircraft factory that stretched for over two miles, with its own
railway system. Its existence remained an official secret until the
1980s.


"fighter aircraft factory" is hyperbolic (probably courtesy of Wikipedia
+ modern journos' disregard for facts): they produced a wide variety of
components and gear for bombers as well as fighters as well as shell
casings and the like; there were no spitfires appearing from tunnels at
Gants Hill with guns loaded on the lines of Blofeld's secret lair


--
Robin
reply to address is (meant to be) valid