6Perhaps the most iconic steam locomotive in the world, the legendary Flying Scotsman was the first train to achieve 100mph and in its glory days ran the only non-stop passenger service between London and Edinburgh. When it was withdrawn from regular service in 1963, after nearly 40 years in service, the locomotive had travelled an estimated two million miles. In January 2016, after a complete and expert restoration project lasting a decade, Flying Scotsman returned to the UK's mainline as one of the jewels in the National Railway Museum's collection.