One of the earliest historical records of the caves is a 13th-century charter, which mentions their use for mining lime-burning chalk and flint. A prehistoric skeleton discovered in the ceiling implies origins dating back to 10,000 BC, when people sought refuge during the Ice Age.

At the start of the 20th century, tourism surged in the area as word spread that the caves perhaps had an ancient history – a theory propagated at the time by William Nichols, vice president of the British Archaeological ᴀssociation.

“When I visited, our guide keenly counted everyone in and out of the tunnels, having handed each of us an oil lantern in case we managed to wander off the path,” said journalist Milo Boyd, who took a guided tour.

“Over the years dogs have been taken down to find those lost in the caverns.”

During the caves’ more recent, post-war use as first a rock and then rave venue (Pink Floyd, the Rolling Stones and Jimi Hendrix all performed), it was not uncommon for hungover revellers to wake deep in the caves’ bowels, having staggered into their depths after one-too-many.

The behaviour of party-goers, who would spill onto the residential streets at 3am after a night in the underground, led to the closure of Chislehurst Caves as a music hall in the early 80s. However, this didn’t completely halt the fun.

One morning, guides discovered missing wall lamps in the tunnels. Upon further investigation, they found that a group of teenage dirt bikers had broken in overnight and used the lights to create a track through the darkness.