Rock is a poor conductor of heat, so this wayward energy travels through it very slowly.

ECONOMIST: The hole story of global warming

Labour have criticised the government's sale of Northern Rock as a poor deal for taxpayers, saying it was sold off at a "fire sale" price.

BBC: Northern Rock: Labour hits out at 'fire sale' price

It also emerged that Sir John Gieve, the deputy governor in charge of financial stability, who came in for criticism for the central bank's poor response to the crisis at Northern Rock, will leave his job early, in 2009.

ECONOMIST: British banks