Imogen

Imogen is a LMS Princess Coronation Class

Season 1:

 * Pilot, Mildred and 1034, Imogen and the notion of trucks

Technical Details of the Coronations:
Imogen is based off the LMS Princess Coronation Class 4-6-2

Construction:
The first five locomotives, Nos. 6220–6224, were built in 1937 at the LMS Crewe Works at an average cost of £11,641 each. They were all intended to haul the Coronation Scot, so the locomotives and the special trainsets bore a common livery. The locomotives were streamlined and painted Caledonian Railway blue with silver horizontal lines along each side of the locomotive. The special trainsets that they hauled were painted the same shade of blue and the silver lining was repeated along each side of the coaches.

In 1938 the second five locomotives of the class, Nos. 6225–6229 (named after Duchesses) were also built in streamlined form at an average cost of £11,323 each. They were painted in the same shade of crimson lake which had already been applied to the Princess Royal class; the same style of horizontal lining that had been a feature of the first five locomotives was continued, but in gilt. Although the crimson lake matched the standard LMS rolling stock, there was no attempt to apply the gilt lining along the sides of these coaches. A prototype trainset was built with such lining for exhibition in America, but it was never put into service due to the outbreak of the Second World War.

Stanier, the designer of the locomotives, felt that the added weight and difficulty in maintenance due to the streamlining was too high a price to pay for the actual benefits gained at high speed. Therefore, in 1938 a third batch of five locomotives (again named after Duchesses) was built, Nos. 6230–6234, without streamlining at an average cost of £10,659 each.

During 1939 and 1940, a fourth batch of ten locomotives (Nos. 6235–6244) was built in streamlined form commencing with No. 6235 City of Birmingham. The names of cities for the locomotives would seem to have been adopted because the LMS was fast running out of names of Duchesses. These locomotives cost an average of £10,659 for the first five and £10,838 each for the second five. The names of the cities in this batch were in strict alphabetical order. This came to an end when No. 6244 City of Leeds was patriotically renamed King George VI in 1941.

The fifth batch, again named after cities, comprised four locomotives, Nos. 6245–6248. These engines were built during 1943 and the average cost was held to £10,908 due to the incorporation of recycled boilers. During the Second World War, the Materials Committee of the government tried to balance the needs for steel between civilian departments and the War Department when allocating those resources. Despite these constraints, the entire batch was still outshopped in streamlined form.

The theme of cities continued into 1944 when another batch of four, Nos. 6249–6252, was built without streamlining. The cost of these locomotives averaged £11,664 each. A follow-up batch of three locomotives (Nos. 6253–6255) was built in 1946 and this batch attracted an inflationary average cost of £15,460 each. The problem of hanging smoke was addressed and smoke deflectors were now incorporated into the design.

The final two locomotives were constructed to the modified design of George Ivatt who succeeded both Stanier, following his retirement, and Stanier's immediate successor Charles Fairburn, who unexpectedly died in office. The first, No. 6256 built in 1947, was the last of the class to be built before nationalisation and it was therefore named in honour of its original designer Sir William A. Stanier, F.R.S.. The unveiling of the nameplate was performed by Stanier himself. In 1948, the privately owned railways were nationalised and incorporated into British Railways. It was within this new regime that No. 46257 was completed – in common with other LMS locomotives, 40000 had been added to the original numbers. The spiralling costs after the Second World War, combined with the design changes, resulted in the individual cost of these locomotives escalating to £21,411.

Smoke Deflectors:
Following a report by George Ivatt in 1945, smoke deflectors were introduced due to drifting smoke obscuring the crew's forward vision. The first locomotive to be fitted with smoke deflectors from the outset was No. 6253 City of St. Albans in September 1946. All the following four locomotives included this feature. The first unstreamlined locomotive to be retrofitted was No. 6232 Duchess of Montrose in February 1945.

Removal of Streamlined Casing:
George Ivatt's 1945 report also recommended the removal of all streamlining casings and they were removed from the fitted locomotives from 1946 onwards. It had been found to be of little value at speeds below 90 mph (140 km/h), and was unpopular with running shed employees as it caused difficulty of access for maintenance. The first step towards de-streamlining was carried out during the Second World War when many of the streamlined tenders had their side sheets cut away at the rear of the tender. Many photographs exist showing this measure. The removal of the streamlining proper commenced in April 1946 with No. 6235 City of Birmingham. All de-streamlining coincided with the fitting of smoke deflectors. No. 6243 City of Lancaster was renumbered as 46243 in April 1948 and, as it was not de-streamlined until May 1949, it became the only locomotive to carry its British Railways number while streamlined.

Initially, locomotives that had previously been streamlined could be readily recognised by the sloping top to the front of their smokeboxes, as well as slightly smaller front-facing cab windows. In due course all were re-equipped with cylindrical smokeboxes and larger cab windows, often, but not necessarily, at the same time. The first locomotive to receive a cylindrical smokebox was No. 6226 Duchess of Norfolk in October 1952. The last one to retain the sloping top was 46246 City of Manchester which appeared with its new smokebox in May 1960.

Even following the conversion to cylindrical smokeboxes, it was still possible to distinguish some non-streamliners from ex-streamliners. On the former (Nos. 46230-46234 and 46249-46252, but not 46253-46257) the running plates veered downwards at right angles to connect with the buffer beam in the style of the Princess Royal Class. The ex-streamliners did not have any such connection, except No.46242 City of Glasgow which was rebuilt in 1952 following a serious collision

VA:
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