The railway line at Tanfield, County Durham, was already a hundred years old when Stephenson’s steam locomotive Locomotion, left Shildon on the opening day of the Stockton and Darlington Railway. Railways had been around for a long time before Stephenson and in many ways the story of the Tanfield line is the story of railways. It began life as a wooden waggonway, built to facilitate the movement of coal from collieries in north-west Durham to the River Tyne and although there were many such waggonways around at the time, it was the greatest of them all, boasting the world’s first recognisable stone railway bridge. Steam locomotives would eventually replace horses on the line and it operated as a conventional railway, albeit with inclines, until the 1960s. However, before it ceased to be part of our national rail network, part of the line was adopted as a steam heritage railway with the result that this is probably the oldest continually working railway anywhere in the world. This is an account of its three hundred working years.