I entered the…tunnel, which was so narrow that my shoulders rubbed against the walls on either side, while the roof was so low that I could not proceed on hands and knees but was forced to crawl along on my chest. Behind me came a doctor on holiday from India, and behind him came Frazer Hearne. The gallery ran for 60 feet into the hillside, and at the far end was a tiny round room, just large enough for me to turn round but not for my companions to do so. Therefore, they had to wriggle out backwards, and, while I do not suffer from claustrophobia, I was scared pink that they might become wedged in the confined space. When wearing an ordinary jacket, it is one thing to go forward, but quite another thing to go backwards. I was particularly apprehensive about Frazer Hearne, for he was the most burly of the trio and he was wearing a rough tweed plus-four suit, and I had horrible forebodings that his jacket would ruckle up from the hem and that he would be trapped in the narrow tunnel.

So wrote Edmund Venables about an exploration of a Sussex flint mine in the 1860s (the Bournemouth Uni article from which I quote erroneously says 1960 – I am convinced that the fashionably dressed shovelbum would not be seen wearing   tweed plus-four suits in the 1960s).

Hard to imagine how the neolithic miners must have experienced the dank tunnels with only their dull smokey torch flames and vindictive dead ancestors to guide them.

Sadly Grimes Graves is the now the only ancient flint mine open to the public, but despite a steep climb down into the pit base, the site has been sanitized and there is nothing of the claustrophobia Venables describes.  Francis Pryor, however, relates a similar moment of terror (in Britain BC) during a visit to Grimes Graves in the 1950s, before they re-grouted the shaft walls and barred up  the tunnel sprites.