In this final episode of the series from Didcot, Dr Hannah Fry and Peter Snow look towards the future of rail travel. Hannah explores how the timetables work and whether they can squeeze in extra capacity in the future. She also looks back to what the future could have looked like had Brunel's broad gauge track system become the standard over a hundred years ago. Engineer Dick Strawbridge meets some young volunteers who are preserving locomotives and learning the engineering techniques to keep the network running, and he is live from Clapham Junction, one of the busiest commuter rail stations in Europe. Tim Dunn is after another live rare spot, a mail train which runs cards and letters around Britain and is powered by a unique class of locomotive. He also gets to ride on a train so futuristic it isn't even on the network yet. Back at Didcot, Peter is joined by Gerry Barney, who designed the British Rail logo, something that has stayed constant through years of rail upheaval and is still a design classic today. Show less