In November 1937, Oliver Vaughan Snell Bulleid replaced Richard Maunsell as Chief Mechanical Engineer (CME) of the Southern Railway. Bulleid was of New Zealand origin, being born there on 19th September 1882, but had mostly grown up in England. He began his railway career in 1901 as a premium apprentice with the Great Northern Railway, working under the guidance of H. A. Ivatt at Doncaster Works. He remained in this role until 1908, when he left to join the ‘’French Westinghouse Company’’ (Société Anonyme Westinghouse). This move led to a significantly higher salary, allowing him to marry Marjorie, the youngest of Ivatt’s daughters, in the same year. Bulleid returned to the GNR at Doncaster in 1912, this time becoming Chief Technical Assistant to the eminent Nigel Gresley (who had succeeded Ivatt as CME of the company on 1st October 1911). Up until this time, Bulleid had also been a Mechanical Engineer for the Board of Trade at continental exhibitions. Gresley became the first CME of the LNER when the latter came into existence in 1923, and Bulleid remained as his personal assistant until his departure to the SR at the age of 55.
Whilst the first months of Bulleid’s reign as the SR’s CME involved bettering the locomotives he had inherited from his predecessor, it was not long before he was able to develop a completely new engine. On 2nd March 1938, the SR’s Rolling Stock Committee authorised the construction of ten new main line steam locomotives; approval was also given by the SR’s Locomotive & Electrical Engineering Department. This decision had been made in spite of the fact that no definite design had yet left the drawing board. For the Eastern Section, Bulleid set himself the target of developing a locomotive that could single-handedly haul a 600-ton boat train between Victoria and Dover Marine, whilst maintaining an average speed of 60 MPH over the entire journey. Up until this time, the target load figure for such trains had been 500-tons on a 55 MPH start-to-stop schedule. Whilst Bulleid’s proposals were beyond the requirements of the SR’s traffic department, the primary need was still that of greater power, to speed up journey times of the heaviest trains. At this time, the ‘’Night Ferry’’ commanded the greatest loading figure, which fluctuated between 400 and 600 tons. Twenty passenger vehicles were allocated to this service, of which up to fourteen were used in a single formation. The remaining six vehicles were split as follows: three under overhaul; one spare in London; one spare in Paris; one spare in Brussels
Reportedly, Bulleid was leaning towards a locomotive with a 2-8-2 wheel arrangement, on a par with the Gresley ‘’P1’’ Class. This was a small class of just two engines, which emerged from Doncaster Works during the latter half of 1925. The pair were designed to haul the heaviest freights on the LNER system, comfortably handling trains weighing 1600 tons upwards. It appears, however, that Gresley went far beyond the requirements of the LNER’s traffic department (as Bulleid latterly did with the SR) when laying out the specifications for the class. There were in fact very few trains on the LNER system which loaded to such a weight, which immediately restricted the usefulness of the engines. Coal consumption was high, whether or not a heavy load was trailing behind, and thus the lack of such giant 100-wagon freights must have made the ‘’P1’’ Class hopelessly uneconomical. These locomotives were latterly culled in July 1945 as a result of the LNER’s standardisation scheme, implemented under the direction of Edward Thompson. He became CME of the LNER after Gresley's death in 1941, and very soon began rebuilding existing locomotives into more conventional forms.
Not put off by the ‘’P1’’ episode, however, Gresley again pursued a 2-8-2 wheel arrangement in the following decade; and so over the period 1934 to 1936 emerged a second class of locomotive with impressive pulling power. Eventually totalling six engines, this became the ‘’P2’’ Class, the first (and surely most renowned) member of which was No. 2001 ‘’Cock o’ the North’’. Unlike their ‘’P1’’ sisters, these were express passenger engines, tailor-made to the Aberdeen to Edinburgh Waverley line. This route was characterised by steep gradients and tight curves, the latter of which an eight driving wheel arrangement was perhaps not best suited. However, as per the ‘’P1’’ Class, the 2-8-2 specification afforded superb wheel adhesion, a necessary ingredient for hauling heavy trains up sizeable inclines. Indeed, such power did come at the cost of disproportionately high coal consumption. Bulleid was heavily involved in the development of the ‘’P2’’, and all six engines eventually received the distinctive streamlined front end found on the Class ‘’A4’’ Pacifics, a design feature jointly credited to Gresley and his assistant. Unfortunately, these engines had an even shorter life in their original form than their ‘’P1’’ counterparts, and similarly fell foul to Thompson’s standardisation scheme. All were rebuilt into more conventional 4-6-2 ‘’A2/2’’ Pacifics during World War II.
The main boat train route on the Eastern Section utilised the ‘’Chatham’’ line via Herne Hill for its early part. From the London direction, this extended as far as Bickley, whence the Tonbridge Cut-Off line via Orpington could be reached through a maze of connecting spurs. Thereafter, the ex-SER line was followed for its entirety, taking a course through the Weald of Kent, then on to Dover Marine via Ashford and Folkestone. In places, the route featured steep gradients and sharp curves, not unlike those faced by Gresley on the Aberdeen line. Indeed, the immediate climb from Victoria to Grosvenor Bridge was formidable at 1 in 64, during which time trains also tackled a series of tight curves. At the eastern extremity of the route was Dover Marine, which resided on the edge of a complicated triangular junction between ex-SER and ex-LC&DR main lines. Thus, by the nature of its location, the terminus’ approaches were formed by a collection of sharp curves, which could create problems for a long wheelbase locomotive. Evidently, Gresley had not been fazed by this hurdle in Scotland, for which a 2-8-2 engine was still procured – perhaps the bends were considered a lesser evil than the climbs.
Deviating from the actions of his erstwhile superior, Bulleid instead opted for the more conventional 4-6-2 ‘’Pacific’’ wheelbase, but not before also outlining a 4-8-2 locomotive. It was considered that the ‘’Pacific’’ arrangement would be met with greater approval from both the SR Board and the Civil Engineering Department, but the scope for innovation nevertheless remained considerable. The aim was to produce an engine with such novelties that the availability of the steam locomotive greatly improved, making it a genuine competitor to diesel and electric traction. As far as Bulleid was concerned, the new locomotives were not destined to be stop-gap measures but, rather, were intended to push the boundaries of steam traction engineering, and hold off the acceleration of electrification and dieselisation schemes. Time was not on the CME’s side, for third rail was spreading quickly. In 1933, the entire Brighton line had become electrically worked and, in 1935, electrification on the Eastern Section as far as Gillingham, Maidstone, and Hastings, had been announced. On the Western Section, lines to Portsmouth via Guildford and Horsham were to be similarly treated. The climate in which Bulleid worked was worsened further by the outbreak of war on 3rd September 1939.
War brought a number of complications. It now became undesirable to develop a new express passenger locomotive, for it was seen as a wasteful extravagance aimed at serving a traffic that was no longer a priority. Secondly, some materials, which would otherwise have been used in the construction of these engines, were now unobtainable. Wartime restrictions favoured the production of freight and mixed traffic engines, which were now required in abundance to haul supplies from far-flung corners of the country to Dover, for use by the Allied Forces on the continent. This invited a loophole in the policy to be exploited to Bulleid’s advantage: he revised the classification of the proposed locomotive fleet from ‘’express passenger’’ to ‘’mixed traffic’’, to ensure a smooth, unhindered build programme. Under the direction of Bulleid, the draughtsmen at Eastleigh’s Drawing Office set to work.
On 18th February 1941, the first completed Bulleid Pacific emerged from Eastleigh Works. On 10th March of the same year, a ceremonial naming took place, in which the engine was christened ‘’Channel Packet’’ by the then Minister for Transport, Lieutenant-Colonel J.T.C. Moore-Brabazon. The Minister drove the locomotive along sidings and up to a train, this of which the engine was coupled to. In addition, he remarked that Bulleid was ‘’not only an engineer, but an artist’’. Artistic indeed, because the locomotive in question was unlike anything previously seen, arguably as striking as Gresley’s Class ‘’A4’’ Pacific when first unveiled. ‘’Channel Packet’’ was the first of an initial order of ten three-cylinder single-expansion high-pressure locomotives, designated the ‘’Merchant Navy’’ Class. Coinciding with the with the launch of the new engines was the adoption of a unique numbering system, conceived by Bulleid:
‘’Channel Packet’’ thus became No. 21C1, and the following engine was numbered 21C2. The latter was ceremonially named ‘’Union Castle’’ on 4th July 1941 but, like its sister locomotive No. 21C1, it had been deployed into service during the previous month on freight duties. There were eventually thirty ‘’Merchant Navy’’ engines, ordered in three batches of ten. They were the first engines to be fully lit by electricity.