Locomotives 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.
Tenders Overview The original design of tender, which came to be known as Type 'A' was designed for the first ten streamlined locomotives. These were of welded tank construction and included side sheets extending from the rear of the tender, which had the effect of reducing drag from eddies between the tender and the leading coach. 28 of these were constructed to be coupled with all the 24 streamliners (Nos. 6220–6229 and Nos. 6235–6248) as well as four of the unstreamlined locomotives (Nos. 6249–6252). In practice, it would seem that the side sheets made it more difficult to access the water filler as well as the couplings. A second, more traditional design followed for the initial batch of five unstreamlined locomotives (Nos. 6230–6234). Again they were of welded tank construction, but lacked any of the streamlining add-ons. Even without the streamlining Type 'B' tenders were distinguishable from Type 'A' by having a slightly different profile at the front and steps and handrails at the rear. The third design, by George Ivatt, initially was Type 'C1' and it was paired with the three locomotives Nos. 6253–6255. It was partially riveted and resembled a Type 'A' at its front end and a Type 'B' at the rear. The design was quickly followed by Type 'C2', which differed from the 'C1' in that it had a lower front edge and was fitted with Timken roller bearings. Only two 'C2's were built and they were coupled to the last two of the class, Nos. 6256 and 46257. Whilst nearly fifteen of the tenders remained wedded to their original locomotives, others received new partners – the very first tender to be manufactured swapped partners seven times. After the Second World War, when the streamlined tenders were de-streamlined, it was difficult to spot any mismatches. The most readily visible mismatches were those of locomotives Nos. 6249–6252 where pre-produced Type 'A' streamlined tenders were married to unstreamlined locomotives. An unusual feature of all Coronation Class tenders was that they were fitted with a steam-operated coal pusher to bring the coal down to the firing plate. When this was in operation a plume of steam could be seen rising from the rear face of the coal bunker backwall. This equipment greatly helped the locomotive's fireman to meet the high demands for power during the non-stop run of between
London Euston and
Glasgow Central, when operating the
Coronation Scot train.
Table of tender and locomotive pairings All LMS tenders were given their own unique identity numbers and they tended to be constructed in advance of the locomotives they would be paired with. Hence, they were made in four batches, Nos. 9703–9709, 9743–9752, 9798–9817 and 10622-10624. The following table lists the locomotives to which they were attached. Of note is the fact that locomotive No. 46221 had its tender (No.9816) withdrawn ahead of time in 1962; the locomotive was then paired to the Princess Royal tender No. 9359 until its withdrawal in May 1963.
Modifications Double chimneys Single chimneys were fitted to Nos. 6220–6234 when built. Following a successful trial using No. 6234
Duchess of Abercorn on 26 February 1939, these were replaced with
double blastpipes and chimneys between 1939 and 1944, the last being No. 6220
Coronation. From No. 6235 onwards, all the locomotives were built with double blastpipes and chimneys.
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 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. These locomotives were affectionately referred to as 'semis'. 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.
The final locomotives The final two locomotives Nos. 6256 and 46257
Sir William A. Stanier, F.R.S and
City of Salford were given many new features. In order to raise the mileage between general overhauls from 70,000 to 100,000, measures were taken to decrease wear to the axle bearings and
hornguides through the use of roller bearings and manganese steel linings. Other modifications included further superheating area, a redesigned rear frame and cast steel trailing truck, rocking grate, hopper ashpan and redesigned cab-sides.
Automatic warning system During the twentieth century,
signals passed at danger (SPADs) were increasingly perceived as a significant danger to the public. Only the
Great Western Railway truly accepted the challenge posed. Prior even to 1910, it commenced installing
Automatic Train Control (ATC), a system where each distant signal was accompanied by a ramp between the tracks with which a shoe on the locomotive would make contact as it passed over it. When the signal denoted "clear", an electric current would pass through the ramp which was detected by the shoe, thereby sounding a bell in the cab. With the signal at danger, the electric current would be cut off and when the shoe detected this it would activate a warning horn. In later forms, the brakes would be applied should the driver fail to acknowledge the warning. In 1952, the UK's most disastrous SPAD ever occurred at
Harrow and Wealdstone, in which No. 46242
City of Glasgow was severely damaged. The lack of an ATC system on most of Britain's railways was at last seen as an urgent issue. From 1956 the BR-designed
Automatic Warning System (AWS) was installed. It was similar to ATC but relied on an induced magnetic field rather than an electric current and featured a visual indicator in the cab. The receiving system was installed on the Coronation class locomotives from 1959 onwards. The outward evidence of on-board AWS comprised a protective shield behind the front screw coupling, a box to house the necessary batteries immediately in front of the cab on the right-hand side and a cylindrical vacuum reservoir above the right-hand running plate. == Table of Locomotives ==