Dorothea was built in 1901 for use at Dorothea Slate Quarry in North Wales. Essentially she was built to the same design as Covertcoat, but she was fitted with a fully enclosed cab along with fastening sliding doors. Dorothea worked until the early 1940's where she was then left atop of a hill in a collapsing shed; she remained derelict until 1964. When she was found, her cab had been removed and used as a blast shelter elsewhere on the Quarry and what was left of the engine was worn and weathered from years of exposure to the elements. The remaining usable parts had been sold off for use on other engines.

 

The rescue of the remains of Dorothea was completed by enthusiast Dave Walker, and Tony Hills, in 1970. Various parts were eventually recovered across the years and collected by Dave Walker at his home in Warwickshire, including the cab which was purchased at a site auction in September 1970 following the closure of Dorothea Quarry.

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By the end of 1975 Dave Walker had acquired the majority of the separated parts to Dorothea. After many moves, he finally settled in Cornwall where Dorothea was 'stored' in the car park of Launceston Steam Railway - A first refusal offer of purchase was given to Dorothea's rescue partner Tony Hills; with him declining the offer, the engine was sold to Nigel and Kay Bowman in 1989.

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Kay was determined to restore Dorothea to working order, much to her husband's doubts - Nigel had seen Dorothea back in 1964 and had concluded it was impossible to restore, so to later see it in working order, furthermore with the restoration being completed by his wife, was something of incredible fate.

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With a drive to complete the work herself using as much original material as possible, Kay worked on Dorothea in her spare time, using some fabricated parts made by Clive Gibbard, son-in-law to Dave Walker. The engine ran for the first time in December 2001, using Covertcoat's boiler and saddle tank and later was steamed in a complete state in November 2011, just in time for the engines 110th Birthday.

For this restoration, Kay was subsequently awarded the John Coiley award for Locomotive Preservation by the Heritage Railway  Association. In a remarkable turn of events, Dorothea was re-united with her original brass works and name plates in November 2013.

 

The engine entered full service in October 2012 following the fitting of air brake equipment. ​The locomotive is still being worked on cosmetically as and when time allows - as of 2021, Dorothea has had her front windows fitted as well as her saddle tank sandboxes.