The West Highland Extension - the "Road to the Isles" is a masterpiece of railway engineering. When filmed, in 1985, the line was still signalled by semaphores. You will see dozens of trackside and footplate shots, as we make our way from Fort William through Mallaig Junction and along the shores of Loch Eil to the famous Glenfinnan viaduct. At the time of construction this was the largest concrete structure in the World. At Lochailort there is a dramatic change in scenery. This part of the line was the most difficult to build with tons of explosive being the only way to drive the railway through the rock. A hundred years on, it is all the more spectacular for it. At Arisaig (Britain's most westerly station) our "Black 5" heads north across Keppoch Moss until we emerge alongside the Atlantic Ocean for the approach to the fishing port of Mallaig.