Most of the steam fleet have had major industrial careers in Scotland, but a few ex-mainline types are also in constant service.

The steam fleet was bolstered in 2006 by the arrival of the Hampshire Narrow Gauge Trust's Bagnall 0-4-0ST 2091 'Wendy'.

In addition to the allocated steam fleet, he said he usually had 3 diesels stabled, plus any which had failed.

In 1958 the British Transport Commission reappraised the speed of the programme, and the decision was taken to accelerate the disposal of the steam fleet.

Some seven hundred 2-8-4s were built for American service, constituting 2% of the steam fleet prior to dieselization and delivering 5% of the nation's freight ton-miles.

After the Second World War, the steam fleet was retired and replaced with war built tugs from the navy.

In 1956, the Pennsy retired the remaining steam fleet and opened bidding for a large order of diesel replacement locomotives.

In 1956 the Pennsylvania Railroad (PRR) finally planned to retire its steam fleet and buy a large order of diesels.

The steam fleet currently comprises over a dozen mainline classes, many of them either heavy freight, express passenger or shunting tank engines.

Over the next 12 years, the entire steam fleet was replaced with first generation diesels.