It's 200 years since the first passenger rail journey saw George Stephenson’s Locomotion No.1 travel 26 miles between Shildon, Darlington and Stockton. Environmentalists love trains - making a journey by rail can be up to 80% greener than doing it by car - and there are exciting new inventions hoping to make train travel even greener. But can we pin part of the blame for global warming on the invention of the railways in the first place?

Presented by Tom Heap and Helen Czerski Produced by Beth Sagar-Fenton Assistant Producer: Toby Field

Rare Earth is produced in association with the Open University