Just so happened that I came across a reference to the July 1880 colliery disaster at Risca, Monmouthshire. One of the theories put forward as to the cause of this disaster, was that gas in the pit was ignited by lightning traveling down the shaft. Although the article implies that not much weight was given to the idea in the context of the Risca disaster, the account given in the document posted by "Christwigg" above seems to show it can indeed happen.
For those of you who are interested, the full account of the Risca disaster can be found here
http://www.cmhrc.co.uk/cms/document/1880_81.pdf I also remember a thread a little while ago which discussed storms, barometric pressure and risk of explosions in mines...
http://www.aditnow.co.uk/community/viewtopic.aspx?t=7055 Relevant info is towards the end: - think I knocked the thread slightly off-topic!
Perhaps this is therefore a good opportunity for still furthur discussion on this intriguing subject.
'I wonder how many breakfasts, and other meals we have missed inside that nasty clockless, timeless hole?'
'The Hobbit'
J R R Tolkien.