Probably the worst non coal mine underground methane explosion in the UK in recent years was the Abbeystead pumping station disaster in (IIRC) the 1980's. A group of villagers from St. Micheal on the Wyre, whom were were now protected from flooding by the station, were blown up during a visit to the scheme. No one envisaged that the tunnel feeding the pumps was in methane baring strata & so the pumps were non FLP. The resulting explosion when the pumps were started for the visit was sufficient to blow the concrete roof of the station.
Sincere apologies to anyone involved for any discrepancies in my post, as it is entirely from memory.
