During the mid to late 1930s the Royal Air Force expanded rapidly in readiness for the looming war. This created a massive storage requirement for its stocks of high explosives, bombs and other ordnance.

The authorities set about locating underground sites around Britain which were considered safe from the threat of aerial attack.

Worked-out limestone and slate quarries were ideal, but in the haste of the moment safety was pushed aside - which, for the RAF in particular, had appalling consequences ...

Fauld

The worst disaster was at Fauld in Staffordshire. A gypsum quarry had been converted to an underground ammunition depot and stocked to over-capacity in preparation for the D-day landings.

At thirteen minutes past eleven on Monday 27 November 1944 four thousand tons of bombs stored underground detonated en masse. The blast took two farms and much of the nearby village of Hanbury with it; seventy men and women lost their lives.

The explosion, which earned the dubious and lasting distinction of being the largest and most devastating on the British mainland, left a crater three quarters of a mile long and half a mile wide.

 Aerial view of the crater left by the explosion

The aftermath of the explosion - damage to the Cock Inn at Hanbury .

Llanberis

Llanberis in north Wales and Harpur Hill in Derbyshire were artificial underground depots which consisted of concrete vaults built in worked-out quarries covered with forty feet of loose rock. But in an effort to save money their construction was under-specified �?with disastrous effect!

On 25 January 1942 an ammunition train was about to be unloaded in the underground sidings at Llanberis when nearly half the depot suddenly collapsed like a house of cards and as the fragile arches gave way thousands of tons of loose rock poured in from above.