Mid-Norfolk Railway Dereham Norfolk by Adam Swaine Via Flickr: The Mid-Norfolk Railway (MNR) is a 17+1⁄2 miles (28.2 km) preserved standard gauge heritage railway, one of the longest in Great Britain.[4] Preservation efforts began in 1974, but the line re-opened to passengers only in the mid-1990s as part of the “new generation” of heritage railways.[5] The MNR owns and operates most of the former Wymondham-Fakenham branch line of the Norfolk Railway.