Whilst on holiday we visited the North York Moors railway near Whitby. I wondered what the longest length of preserved railway line is in Britain, and does someone have a handy list. The answer seems to be no.
So here is my list, which is neither complete, nor comprehensive. For a complete list, see Wikipedia.
| Standard Gauge lines – Name, where it runs | Miles | km |
| West Somerset Railway, Minehead to Bishops Lydeard (near Taunton) | 22.75 | 36.6 |
| Wensleydale Railway, Northallerton to Redmire | 22 | 35 |
| North York Moors Railway, Pickering to Grosmont (see below) | 18 | 29 |
| Severn Valley Railway, Kidderminster-Bewdley-Bridgnorth | 16 | 26 |
| Mid Hants Railway “Watercress Line”, Alresford to Alton | 10 | 16 |
| Bluebell Railway, East Grinsted to Sheffield Park (near Haywards Heath) | 11 | 18 |
| Epping and Ongar Railway | 6 | 10 |
| Narrow Gauge Lines – Name, where it runs | ||
| Leighton Buzzard Light Railway (2′ gauge narrow gauge) | 3 | 5 |
| Welsh Highland Railway (Caernarfon-Porthmadoc) (2′ gauge narrow gauge) | 25 | 40 |
| Ffestiniog Railway (Porthmadoc-Ffestiniog) (2′ gauge narrow gauge) | 13.5 | 22 |
Some trains on the NYMR run through Grosmont into Whitby, adding another 7 miles to the route. This would make the NYMR the longest preserved line in Britain, as well as the busiest in the world.
Based on my very limited research, the longest length of preserved railway in Britain isn’t standard gauge, but is the combined WHR and Ffestiniog Railway. Thus the oldest surviving railway company in the world is also Britain’s longest heritage railway.