By C Pailin

This impressive locomotive is a 5” gauge model of the LMS City of Coventry shown by C Pailin at a Midlands Model Engineering Exhibition. The model has four cylinders of 1.5” bore x 2.5” stroke with 13/16” diameter piston valves controlled by outside Walschaerts valve gear with rocker shafts to the inside valves. Driving wheels are 7.125” dia.

The boiler operates to 90psi, has 18tubes of 5/8” dia, and four 1” dia superheater flues. Grate area is 52 sq in. The model is 6’ 7” long and weighs 7cwt.

The Duchesses were the most powerful steam locomotives ever built in the United Kingdom. Designed by William Stanier they were unstreamlined versions of the Princess Coronation class. All produced 3,000 horsepower.

They were nearly 74 ft long and weighed in at 105.25 tons without the streamlining. With four cylinders and Pacific 4-6-2 wheel arrangement, these are large and complex engines to model, but several designs have been produced in various gauges.

The first five locomotives, Nos. 6220–6224, were built in 1937 at Crewe. They were streamlined and painted Caledonian Railway blue with silver horizontal lines to match the iconic Coronation Scot train they were built to haul.

Prior to the introduction of the Coronation service, No. 6220 underwent speed trials and reached a speed of 114 miles per hour (183 km/h), beating the previous record for a steam train.

The second five locomotives of the class, Nos. 6225–6229, were also streamlined, but were painted in the more traditional crimson lake, with gilt horizontal lining to match the standard LMS stock. The next batch was built without streamlining. Several more were then completed during the war and were turned out in unlined black. The last two locomotives were constructed by Ivatt to a modified design with roller bearings, and were built in 1947 (No. 6256) and 1948 (No. 46257).

Single chimneys were initially fitted to Nos. 6220–6234 when built. These were replaced with double chimneys between 1939 and 1944. From No. 6235 onwards, the locomotives were built with double chimneys.

Smoke deflectors were added from 1945 due to drifting smoke obscuring the crew's forward vision. The last five locomotives were completed with smoke deflectors fitted.

Three Duchesses have been preserved. 6229 Duchess of Hamilton, 6233 Duchess of Sutherland have both been in service on main line rail tours and No 6235 City of Birmingham is now at the National Railway Museum.



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