TfL testing a world-first idea for cooling the London Underground

The famously hot parts of the London Underground could become a lot more pleasant to use if a new way of cooling the tube proves to work, and the money is found to install it in tube stations.
When the tube tunnels were first dug they were so cold that the fact that the tube offered a respite from the hot sun was a selling feature in early adverts. However, over the past century, the cool clay that surrounds the tube tunnels has absorbed so much heat that it can’t soak up any more heat, an