RedBaron,

Would you say that by closing all the mines and thus leaving the coal in the ground for future generations (post cheap oil) Margaret Thatcher was securing the UKs coal resources?

This was perhaps not the route that the NCB and NUM would have taken...

Nick.

Its hard to tell if this was the intent but it seems this may have been the outcome.

On the contrary. When you close a colliery, the underground roadways collapse. There is no longer a route between the shaft and the workable seams. This coal is probably sterilised forever. Thatcher's energy policy, like her economic policy, was vandalism based on the belief that wet pavements cause rain.

Red Baron:
The stability of the mine after it is abandoned is controlled by a lot of different factors - including whether or not the mine then floods. There have been mines that have been re-entered years later that are still stable. Caves are an illustration that openings can stay stable without human intervention. In large measure it depends on how large the pillars are when the mine is abandoned. In areas that have been longwalled the roof has collapsed already, and those areas cannot realistically normally be revisited (though they can if you are doing multi-pass extraction and had filled the empty space with waste - though this is quite rare). It also depends on the ways in which they held up the rock over the roadways,

UK colliers were entirely longwall and roadways were supported by steel arches. The earth moves and if buckled arches are not replaced the roadway roof falls preventing access to the coal reserves. Now one one need to sink a new shaft , say 3 years, and you cannot speed this up with a Chinese army approach because there is only a few square meters to work in. Then lower roadway supports and blast out roadways underground. Everything is sequential and takes about 9-10 years if you have a skilled workforce -which the UK has lost. So now the UK faces "peak oil" with no secure alternatives. Short the Pound sterling too.