This locomotive was developed during the first half of the 20th Century as an incremental upgrade from a previous highly successful freight engine. A larger boiler was fitted, running at higher pressure. To keep within a tight axle load, an additional axle was also added.
Thousands of these locomotives were built, and while they were quickly displaced from mainline freight, their light axle load ensured a long career on secondary lines.
Can you guess what the mystery train is?
Stay tuned!
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