Guinevere was started in 2001 as a father and son project.
The engine is based on Horton but fitted with Walschaerts valve gear, a larger boiler and larger cylinders, making it a more capable locomotive by combining attributes of Horton and Hartfield.
The engine took 13 years to construct – it was completed in July 2014 and named at the Railway Open Day in March 2015.
The livery is blue with red lining and takes its name from the wife and queen of King Arthur in the Arthurian legend.