A small historical note that may be of interest and available to possibly sort out any confusion that could arise in the future - cavers of the 1940/50's era knew Gentlewoman's Pipe under a completely different name altogether, we knew it as Queen's mine. (See my earlier note under the Midlands Forum Topic "MASSON CAVERN RECALLED - HAPPY DAYS" 16/10/08 on how we obtained access to Queen Mine through Masson Cavern).
At the time of our exploration of the Masson complex Derbyshire Stone Limited were working Masson Opencast for fluorspar, and the Pearson miners (father and son) were working Black Ox underground, also for fluorspar, so it was quite dicey exploring, one never knew what would disappear before the next caving trip! Youds Level had not then been discovered so the only access to Queen mine/Gentlewoman's Pipe was through Masson via Crichman's mine.
Edit - The Masson mines complex and access was completely altered, after Laport received planning consent to carry out open casting extraction for fluorspar extraction on a much larger scale in the disused Derbyshire Stone quarry on Masson Hill in late autumn/early winter of 1978. I am not aware if cavers could still access Queen mine/Gentlewoman's Pipe until then, or if by that time the boulder under which we crawled had collapsed and blocked our route in. It would be interesting to know.
p.s. Thanks for the lovely photographs, greatly appreciated, brought back memories of tight sough crawls!