Britain used to rely almost exclusively on coal for its electricity generation, mining it in Wales and the north and central part of England, then bringing it, usually by train, to power stations where it could be burned to heat up water that would generate electricity. Then the water was cooled down in cooling towers that can still be seen in many parts of the country.

Deep under Whitehall – the home of the United Kingdom’s major government departments – is a secret lair to rival anything created by a James Bond baddie intent on world domination. The Churchill War Rooms were constructed secretly as the bomb-proof centre of wartime government. Churchill was initially reluctant to go underground but he fought fascism here from 1939 to victory in 1945. With him was his wartime coalition ‘cabinet of all the talents’, his senior chiefs and advisors - and a small army of military and civilian staff, all engaged in top-secret work.