document: Kellingley Colliery in North Yorkshire closed in December, bringing to an end centuries of deep coal mining in Britain.
  Ten former workers were part of a team which filled the mine shaft with concrete.
  It took three hours to fill the pit, BBC Look North Business correspondent Danni Hewson said.
  A pipe from the centre of the pit was left to release methane gas, used by the on-site power station.
  The remaining mine buildings will be demolished, and hundreds of houses could be built on the site within a couple of years, it is understood.
  Much of the mine machinery was saved for a new, smaller drift mine nearby - the New Crofton Co-operative Colliery near Wakefield in West Yorkshire which is due to open in June.
  A memorial to 17 miners who lost their lives at the colliery is being transferred from the colliery to the National Coal Mining Museum in Wakefield.
  Known locally as the Big K, the largest deep pit in Europe was hailed as the new generation of coal mining and could bring up to 900 tonnes an hour to the surface.
  Official figures from the Department for Energy and Climate Change show the UK imported more coal than it produced for the first time in 2001 - a trend repeated every year since 2003.
  In 2003 the UK produced 28.28m tonnes and imported 31.89m.
  The graph below shows how output and imports have changed, with the big dip in 1984 due to the miners' strike.
summary: The last deep coal mine in the UK has been capped off, three months after its closure.