For a while during the mid 1980s Class 20s worked the heavy limestone trains in the Peak District, replacing Class 25s and 40s, but before the introduction of Class 37s. Indeed in 1986 a batch of Class 20s were renumbered into the 203xx series to denoted that they had been specially modified for these workings. Prior to this, on 19 June 1984, 20077 & 20172 are seen passing Chinley with the 6F42 13:11 Tunstead to Oakleigh ICI limestone.