Some interesting further information here (Yorkshire Ramblers' Club Journal Volume 7 Number 25, 1949):
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www.yrc.org.uk]
"Large quantities of snow lay for months of 1947 in Pillar Pot and notably in Eldon Hole."
No idea where Pillar Pot is.
Also, is this a new one on Dun Fell near Cross Fell? The mine in question is located at an altitude of about 700m, 1km south-west of the summit of Dun Fell in Cumbria:
"Westmorland, Dun Fell. - Gowing was one of a party of members of the Mineralogical Society who were able to visit the Silver Band Barytes Mine at the invitation of the owners, Messrs. B. Laport, Ltd. The mine is situated at about 2,300 ft. O.D. on the western slopes of Dun Fell, next S. of Cross Fell, and access is by lorry road from Knock running up the side of the mountain. The workings date from the 17th century, but the present main levels were driven by the London Lead Company, who took over the property in 1820 and who carried out some 17,500 feet of development. At the time of the visit there were still large quantities of snow left from the great storms of early 1947 and the levels were entered through snow-tunnel 'extensions'."