Brakeman - By coincidence I was just thinking similar thoughts about the early soughers as I looked through all the photos of Youds Level/Ringing Rake/Masson sough on both Mine sites. My caving son has been up this sough a few times but I didn't appreciate just how tight and long it was.
The soughers worked in tight, claustrophobic, wet, often bad air conditions for the minimum amount of money which was not paid weekly but on the reckoning system (the same as the lead miners) whereby they costed their price for the work in advance, this would be for a set period of anything from six to twelve weeks. They must have been a tough bunch of miners who in turn turned into soughers and adventurers, but the adventurers were mainly the larger lead mine owners and smelters who invested their money in driving the soughs to reach the remaining lead deposits left beneath the water table when workable deposits started to run out in the 17th & 18th centuries. A lot of money could be made or lost through this kind of enterprise, which accounts for when I was young a common expression in Derbyshire when people wasted their money was to say that "they'd thrown their money down a sough!". In the early narrow soughs the mining method was mostly hand drilling (from memory gunpowder for blasting was introduced into Ecton around 1670 wasn't it?) often through hard barren rock such as the "toadstone" beds (volcanic rocks such as basalt, dolerite) also shales (Hillcarr sough is a very good example of this with additional costing for gritstone lining the walls and roof of the sough when driven through the shales which also produced gas and on one occasion caused an explosion and deaths). The "toadstones" separate the Matlock limestones, this is why the sough passages are "coffin" shaped, they took out the bare minimum of rock to save on their costings for the work. Another thing we forget is that people in years gone by were of smaller statute and would have fitted into these narrow passages better than present day mine explorers.
Nellie Kirkham always told me that Derbyshire lead miners who moved abroad to work, were renowned for their drainage expertise in the use of tunnels, whereas Cornish miners were renowned for their engines.
p.s. I know of a much tighter and horrible trip, a crawl all the way over a flowstone floor on one's tummy - I was told it was like crawling over knife blades all the way. My old club "Op Mole" in the late 1950's explored Harvey Dale Tubes in Matlock, there was no standing whatsoever, no crawling on knees, just tummy and elbow work all the way to the end. Part of the way in they encountered and crossed the main drawing shaft of Seven Rakes Mine, the one driven in "toadstone" which is one of the very few reported cases in the Derbyshire lead field (the Queen's/King's Field) of lead veins being found and worked in the "toadstone". At the end of the Tubes my caving buddies had to singularly squiggle round in a minute chamber to turn to come out, one of the Group got stuck doing this manoeuvre, became panic stricken and couldn't move, eventually they made him strip down to his pants and pulled him out from the chamber by a sling losing my carabiner in the process, also tearing his skin badly but they got him out. I didn't go on this trip, I was left at the entrance to call out Cave Rescue in case of an accident! I think the entrance to this system has now been sealed!