"It's over 150 years since climbing developed as a sport and in that time Britain's great crags have been thoroughly explored. In their search for bold new routes, two of Scotland's best rock athletes, Dave MacLeod and Alan Cassidy, travel south of the Border to the heart of the English climbing scene.

In an astonishing week, they attempt two innovative first ascents - one deep underground and the other in a huge cavern. This film follows them as they inch their way from darkness into light."

The pair climbed out of two limestone caves - Jingling Pot and the huge show cave of Peak Cavern.

Dave MacLeod described the TV shoot on his blog late last year:

"Peak Cavern, otherwise known as 'The Devil's Arse' is one of the biggest and most impressive limestone crags in the Peak. In a region where every other inch of rock has a route on it, it's pretty amazing that there are no free routes on this crag at all. It comes down to access. The crag has been banned for climbing forever as it's a tourist attraction on private land - paying public walking around below climbs etc. Of course it's a massive shame since I'm certain a way round it could be found with the help of the BMC. The cave is only open to the public until 5pm and then it's locked. Climber's lock-in? Sadly I don't think a change is likely any time soon. We appealed as best we could."

And Dave went on to explain:

"Anyway, we enjoyed our special permission while we had it, in the name of making BBC television. But first we spent two days a bit further north climbing an even sillier cave. The team wanted to see if we could climb our way out of a proper Yorkshire Pot Hole - Jingling Pot. A 60m tubular soaking wet pitch black slimy hole in the ground...

After that we headed to the main event at Peak Cavern. Where Jingling Pot felt about E3 in the wet, Peak Cavern looked about 9c! The cave went in for over 100 metres...

After a hardcore couple of days with the hilti and wire brush, It looked amazing: 7c+, 7a, 7b+, 7b. Only one problem, the first pitch would be 7c+ if it was dry. But it was completely soaking and all the holds were full of slimy wet mud - proper caving style!"

• More on Dave's Blog and on the BBC Website

Of note is that several aid routes already exist in the cavern (one is pictured above) and Dave Williams has recently added two fairly major aid lines.

• For full details of Dave's aid routes and a bit of history of climbing in the cavern, see his blog: Aid Climbing Blog

Dave MacLeod is sponsored by GORE-TEX , Scarpa , Black Diamond and Mountain Equipment

Alan Cassidy is sponsored by Five Ten, Podsacs, The Climbing Academy, CragX