Very professional railway this, in both senses of the word. Not only is it commercially run without any volunteer assistance, it is also run pretty much as it would have been back in the days of steam.
The rolling stock and engines are all appropriate to the line, with none of the excesses of enthusiasm that some of the volunteer lines are prone to.
Check the Paignton and Dartmouth Steam Railway's website for opening times etc.
Despite the name, the steeply graded line actually runs from Paignton to Kingswear on the other side of the River Dart from Dartmouth. From here you catch the ferry to Dartmouth Station, which sits forlornly on the quayside awaiting the arrival of a line down the west side of the river that was never built. It's now a second-rate restaurant.