By the time that the Somerset and Dorset Railway started to build its Bath extension in the early 1870s, the failing enterprise was increasingly short of money. Conditions on the engine footplate in the mile long Combe Down tunnel must have been like a scene from Dante's Inferno, with choking dust, smoke, fire and steam. In 1966, the line was closed and its days as a transport link seemed gone forever. Yet in 2013, it was reopened, this time as one of the 'Two Tunnels', the longest cycling and walking tunnel in Britain. The author met Mayer Hillman, a researcher at a London think tank called Political and Economic Planning (PEP) in the 1970s, when his university tutor suggested that Hillman might be a useful contact for a planning thesis.