In an attempt to combine large driving wheels with a low center of gravity, No. 3020 “Cornwall” of the LNWR was one of the most complicated, but unsuccessful designs. Designed by Francis Trevithick, son of the famous Richard Trevithick, it was a 4-2-2 with driving wheels of 8 ft 6 in (2,591 mm) built in 1847. To keep the boiler low, but out of the way of the driving axle, it was placed below this axle.

Original state from 1847 with a low boiler

Even though the driving axle could be held out of the boiler, the trailing axle went through a tube in the firebox, what created some problems when assembling the locomotive. Another problem was the long rigid wheelbase that effected the running characteristics. For these reasons, John Ramsbottom rebuilt it into a conventional 2-2-2 with boiler above the driving axle. 

Sectional frawing of the original state

Although it was only a single locomotive, the rebuilt “Cornwall” was used successfully in express service. With light trains, it delivered average speeds of 50 mph (80 km/h) and top speeds of up to 70 mph (113 km/h). In the 1870s, it got a semi-open cab.

It remained in regular express service until 1902. After that, it was not retired, but used as an inspection locomotive. For this task, it got a six-wheel carriage whose front part filled the task of a tender, while its rear part was a passenger compartment. When it reached its final retirement in the twenties, it was one of the first locomotives to be preserved on purpose. Today it can be found in the Buckinghamshire Railway Centre.