Round about three decades ago, I went to south Wales to the Llangattock specifically to go underground with a friend – Kevin Walker – who ran a local outdoor pursuits centre. He took me into ‘Aggy’ – Agen Allwedd – part of a system that may one day all be joined up, and which will then extend for over a hundred kilometres. But that part of south Wales already has vast systems.

Caving and its vertical cousin  pot-holing provide the possibility – almost in anyone’s backyard – of exploration the like of which you’d only otherwise get on the moon or in the ocean abyss. You are totally reliant on your light and on your skills in navigation in three dimensions where the way in – and out – can be above, below, behind or in front of you. It is a magical space that forces you to conquer your worst fears – of confinement, of the dark and of huge open spaces – some as big as St Pauls cathedral.

Caving remains an adventure apart because so few do it; those that do are thankful for that. The two high spots – so far – for me was that Aggy trip, because we went eventually through a tight squeeze to come out into an ancient river bed the size of a train tunnel than ran for miles and miles. The other was going some of the way into the Little Neath River cave in south Wales with my oldest son, Olly, who has gone on to undertake amazing feats of very deep caving with the Cambridge University Caving Club, particularly with their annual expedition to Austria, and the system they explore there. The Little Neath system entrance is in the river bed; we had to turn back, that day, because of time, but what a thrill, pushing our way through a raging torrent to come out eventually into a huge system that went on and on.

What could have been the low spot was in the Mendips when another companion – Mary – got stuck below me and could not pull herself up. I had to make that awful decision to call cave rescue . That is, I had to leave her behind, get out on my own, call out Mendip Cave Rescue,  and then go back and wait with her. Mendips CRO were great and so was she; in the end she exited under her own steam and was none the worse, just cold and wet. Hot tea at the rescue HQ sorted us all out.