Cool £10,000 for ideas on reducing Tube heat

The Mayor of London has offered a £10,000 prize to the first person who comes up with a viable way of cooling down the capital's Tube trains.

Ken Livingstone offered the money a day after thousands of commuters were forced to endure temperatures of nearly 100F for more than an hour when their Victoria Line trains became stranded in a tunnel.

He admitted that no one knew how to cool down deep Tube lines because installing air-conditioning on the trains would simply transfer the heat out into the tunnels.

"It just builds up and it's not like New York or Paris where there are quite big spaces and they're just sub-surface," he told Capital Radio.

He said that his prize offer was a genuine one, adding "part of the problem is that everyone who's looked at it so far has been stumped".