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SR Merchant Navy Class^[1]

Power type	Steam
Designer	Oliver Bulleid
Builder	SR Eastleigh Works
Build date	1941–1949
Total production	30
Configuration	4-6-2
Gauge	4 ft 8½ in (1,435 mm)
Leading wheel size	3 ft 1 in (0.94 m)
Driver size	6 ft 2 in (1.89 m)
Trailing wheel size	3 ft 7 in (1.12 m)
Length	69 ft 8 in (21.85 m)
Weight on drivers	63 tons !64 tonnes)
Locomotive weight	94.75 tons (96.3 tonnes)
Fuel type	coal
Fuel capacity	5 tons (5.1 tonnes)
Water capacity	5000 imp. gal (22700 litres)
Boiler pressure	280 lbf/in² (1,930 kPa)
Fire grate area	48.5 ft² (3.44 m²)
Cylinders	3
Cylinder size	18 in × 24 in (41.6 cm × 61 cm)
Tractive effort	37,513 lbf (166.86 kN)
Career	Southern Railway (Great Britain), Southern Region of British Railways
Class	8P
Locale	Great Britain

The SR Merchant Navy, or MN class was given the nickname "Spam Cans" or "Packets" by locomotive drivers after the doyen of the class, was originally a class of air-smoothed 4-6-2 steam locomotive designed for the Southern Railway by Oliver Bulleid. The original intention had been to build an eight-coupled machine, the first suggestion being for a 4-8-2, quickly modified to a 2-8-2 with a Krauss-Helmholtz "bogie Bissel". Both these propositions were resisted by the civil engineer, so a 4-6-2 Pacific was settled upon. The first members of the class were constructed during the Second World War, with the final total eventually amounting to 30 locomotives. The class was named after Merchant Navy shipping lines involved in the Battle of the Atlantic, and latterly those which used Southampton docks. This was an astute publicity masterstroke for the Southern Railway.

The SR West Country and Battle of Britain, or WC and BB Classes, also known as Bulleid 'Light Pacifics' or by the same nickname as the MN: "Spam Cans", are classes of 'air-smoothed' 4-6-2 steam locomotive designed for the Southern Railway by Oliver Bulleid.

Due to problems with some of the more novel features of Bulleid's design, all members of the MN and 60 of the light Pacifics class were subsequently rebuilt by British Railways during the late 1950s. Some of the Pacifics operated until the end of Southern steam, in July 1967, and a third of the rebuilt MN class along with 20 Light Pacifics in both forms have been saved from scrapping, and can be seen on heritage railways and the mainline throughout Britain.

Contents 1 Background 2 Construction history 3 Construction history 4 Naming the locomotives 5 Livery and numbering 5.1 Southern Railway 5.2 Post-1948 (nationalisation) 5.3 Preserved 'Light Pacifics' 6 Gallery 7 Footnotes 8 References 9 Further reading 10 See also 11 External links

[edit] Background

The gestation of the Merchant Navy Class Pacifics went as far back as 1938, when Sir Eustace Missenden, the Director of the Southern Railway, realised that the company lagged behind in terms of pioneering locomotive design.^[1] Bulleid, who had been brought in from the LNER to replace Richard Maunsell as Chief Mechanical Engineer (CME) believed that it was time for the Southern to lead the field with a new Pacific design.^[1]

This was due to the fact that the newest locomotive class on the railway was an 0-6-0 Q Class that was built to Victorian principles.^[2] Intended primarily for express passenger and semi-fast work in South-East and South-West England, the new class was also designed to be equally adept at freight workings due to the nominal 'mixed traffic' classification Bulleid applied to the class for them to be built in wartime.^[1]

Representing one of the ultimate developments in British steam locomotive technology, these were amongst the first British designs to utilise welding in the construction process, and to use steel fireboxes, which meant that components could be easily constructed during the wartime and post-war economies.^[3] They incorporated many innovations that revolutionised British steam locomotive design, such as thermic syphons along with inside drive and three sets of valve gear driven by chaind all encosed in an oil bath.

From 1945 a considerably lightened version the Merchant Navy design was introduced with increased route availability for use on the Southern's 'Withered Arm' West of Exeter as Merchant Navy Class locomotives were banned from this section due to weight restrictions.^[4]. The Light Pacifics were divided into two groups, the West Country (WC) and the Battle Britain (BB) classes. The first batch of the latter group were intended for the South-Eastern section and had narrower cabs to make them suitable for the tight tunnel on the Hasting line.

[edit] Construction history

Initially, ten were built as mixed-traffic locomotives from 1941, the first being 21C1 Channel Packet. ^[5]They were classed as such for Bulleid to traverse the ban on the construction of express passenger locomotives imposed by the government during the war.^[6]

All locomotives were constructed at the former London and South Western Railway works at Eastleigh, two batches of MN being constructed under the auspices of the Southern Railway. The boiler design was also one of the first in Britain to incorporate welding and steel into the fabrication of the firebox, as the usual material was copper.^[4] This done for cheaper construction and easier maintenance, whilst thermic syphons were implemented to improve the efficiency of water flow within the boiler.^[4] especially when negotiating changes in gradient. The boiler was rated at an operating pressure of 280 psi.^[7]. As regards the WC/BB light Pacifics, weight was saved from use of a shorter boiler which in turn required shorter frames, resulting in a reduced-length locomotive and further weight-savings.^[7] All the Bulleid Pacifics sported the novel, if highly troublesome, chain-driven valve gear[1][2], and were provided with 'air-smoothed' casings and Bulleid-Firth-Brown cast steel wheel centres. The 'air-smoothed' casing was not regarded as streamlining, a fact demonstrated by the extremely flat front end, but as an aid to cleaning the locomotive via the use of a carriage washer, representing another attempt to reduce labour during the post-war period.^[8] Electric lighting was also provided, powered by a steam generator below the footplate, as well as a steam operated treadle that used steam pressure to open the firehole doors as an aid to the fireman.^[4]. The footplate was frequently regarded as ergonomically superior to other express passenger locomotives, as the controls required for operation were grouped according to the particular needs of fireman and driver.^[4] Other innovations included on the footplate included electric lighting and gauges lit by ultra-violet light, which enabled clearer vision of pressure within brakes and boiler at night.^[4] The footplate was also entirely enclosed, representing a step forward in terms of crew working conditions in winter, whilst the supporting trailing truck gave the smoothest of rides, and its design was utilised in the future BR standard class 7. The footplate received modifications after a short period in service, entailing a redesign of the spectacle plates. These are the small windows in the front face of the cab, which were redesigned to the angled profile that all Bulleid-designed locomotives depict post-nationalisation. Originally, the spectacle plates were at right-angles to the air-smoothed casing, offering limited vision ahead for the driver.^[9]

[edit] Construction history

The Southern-built batch years were as follows:

• 21C1-21C10: Completed 1941-1942

• 21C11-21C20: Completed 1944-1945

Both Southern-built batches had detail differences, the latter having a horizontal ridge in the air-smoothed casing, and certain design features were removed, such as the steam operated firehole door treadle. The entire class was subjected to modifications during the brief time they operated under the Southern Railway. The main change being the redesign of the footplate spectacle plates, the small windows in the front face of the cab, which were redesigned to the angled profile that all Bulleid-designed locomotives depict post-Nationalisation. Originally, the spectacle plates were at right-angles to the air-smoothed casing, offering limited vision ahead for the driver.^[8] The Southern Railway constructed 70 Light Pacifics at Brighton Works: the first, prototype West Country Class locomotive 21C101 Exeter, was completed in May 1945; the last was Battle of Britain Class number 21C170 Manston, in November 1947. The Southern-built batches had a narrower footplate than those constructed later, due to the intention for the type to work the width-restricted Hastings Line between Tonbridge and Hastings. In the event, the type was never used on this duty.^[10]

SR Un-rebuilt West Country/Battle of Britain Classes^[11]

Un-rebuilt West Country Class 21C123 Blackmoor Vale, as preserved, in Southern Railway Malachite Green and "Sunshine Yellow" livery, and featuring part of the Golden Arrow insignia
Power type	Steam
Designer	Oliver Bulleid
Builder	SR Brighton/Eastleigh Works
Build date	1945–1951
Total production	110
Configuration	4-6-2 ("Pacific")
Gauge	4 ft 8½ in (1,435 mm)
Leading wheel size	3 ft 1 in (0.94 m)
Driver size	6 ft 2 in (1.89 m)
Trailing wheel size	3 ft 1 in (0.94 m)
Length	67 ft 4¾ in (20.26 m)
Weight on drivers	56.25 tons (56.9 tonnes)
Locomotive weight	86 tons 12 cwt (87.4 tonnes)
Fuel type	coal
Fuel capacity	5 tons (5.1 tonnes)
Water capacity	4,500 imp. gal (20,430 litres)
Boiler pressure	250 lbf/in² (1,723 kPa)
Fire grate area	38.25 ft² (3.44 m²)
Cylinders	3
Cylinder size	16.375 in × 24 in (41.592 cm × 60.959 cm
Tractive effort	31,000 lbf (137.894kN)
Career	Southern Railway (Great Britain), Southern Region of British Railways
Class	7P/5FA
Locale	Great Britain

The final 40 Light Pacifics were constructed after the nationalisation of the railways in 1948. This meant that they never carried Southern Railway numbers.^[11] The British Railways batch had detail differences to previous versions; the most significant being the footplate, which was widened to 9 feet;^[12] and the tender, which had an increased water capacity of 5,500 gallons.

[edit] Naming the locomotives

The Southern Railway considered naming the MN locomotives after victories of the Second World War to the extent that a mocked-up nameplate "River Plate" was produced.^[13] In the event, the chairman of the Union Castle Line suggested naming them after shipping companies which had called at Southampton Docks in peacetime.^[14] This idea had more suitability in 1941 due to the fact that the shipping lines were heavily involved in the Atlantic convoys to and from Britain during the Second World War.^[13]

The two classes are mechanically identical, the class distinction between "West Country" and "Battle of Britain" being purely concerned with the theme of the names given to the individual locomotives. As built by the Southern Railway, 48 of the class were named after places in the West Country served by their trains, and the rest took their names from RAF squadrons, airfields, commanders and aircraft that participated in the Battle of Britain. ^[13] This represented a publicity success due to many of the locomotives being able to visit their namesake areas.^[13]

Many of the West Country locomotives sported an additional plaque depicting the coat of arms associated with the town or region the locomotive was named after. This plaque was mounted on the casing between the locomotive nameplate and "West Country Class" scroll, above the middle driving wheel.

Several members of the West Country Class were issued with only the nameplate and the "West Country Class" scroll, a corresponding gap being left between the two where a crest would have been mounted. ^[15] The background of the nameplate was usually painted red, though sometimes examples could be found in black if the locomotive works undertaking overhaul of the engine could not locate the correct colour paint.^[16]

The Battle of Britain Class nameplates incorporated the name of the locomotive, with the class name below, in a design that resembled the wings of an aircraft. This was painted air force blue, though other colours were sometimes substituted for the same reasons as above.^[17] A crest of the aircraft, personality or squadron was placed below the nameplate, in the same position as the West Country Class equivalent. Incidentally, the nameplates were constructed from sheets of gunmetal.

The original Southern Railway classifications for the two classes were 'WC' for the West Country Class and 'BB' for the Battle of Britain Class, rather than the terms 'BoB', 'BOB' or 'BofB', which are common misconceptions in published works on the topic.

[edit] Livery and numbering

[edit] Southern Railway

Livery was Southern Railway Malachite Green with "Sunshine Yellow" horizontal lining and lettering. All class members that operated during the Second World War were eventually outshopped in Southern Railway Wartime Black livery, with green shaded 'Sunshine' lettering. However, this was reverted back to Malachite Green upon the ending of hostilities.

21C 1 Channel Packet originally had an inverted horseshoe on the smokebox door, indicating its Southern origin, however, locomotive crews believed this to be 'unlucky.' A resultant re-design meant that this became a roundel, the gap being filled by the date and place of construction, therefore acting as a builder's plate. The background was painted red. Early members of the class had cast iron numberplates and gilt 'Southern' plates on the tender, however these were subsequently replaced by transfers.

Bulleid advocated a continental style of locomotive nomenclature, based upon his experiences at the French branch of Westinghouse Electric before the First World War, and those of his tenure in the rail operating department during that conflict. The Southern Railway number followed an adaptation of the UIC classification system where "2" and "1" refer to the number of unpowered leading and trailing axles respectively, and "C" refers to the number of driving axles – in this case three. All the locomotives therefore carried the prefix 21C.^[13]

[edit] Post-1948 (nationalisation)

Initial livery after nationalisation in 1948 was modified Southern malachite green and sunshine yellow with "British Railways" on the tender, and the Bulleid numbering system was temporarily retained with an "S" prefix such as S21C1. The second livery carried was the British Railways Experimental Express Passenger Blue with red or white lining, and was carried until 1952. From then on, the locomotives carried British Railways Brunswick Green livery with orange and black lining, and this livery was perpetuated after rebuilding. The locomotives were renumbered under the British Railways standard system in the series 35001–35030 from 1949.^[18] The British Railways standard numbering system placed them in the series 35021–35030, and the batch was completed at Eastleigh between 1948–1949. The British Railways batch had detail differences to the Southern Railway-built versions concerning fuel and water capacity.

The first Light Pacifics constructed under the new regime were in the Battle of Britain Class, numbers 34071–34090, although naming policy reverted back to the West Country Class from 34091–34108.^[19] The final two constructed by British Railways were once again BBs, these being 34109 Sir Trafford Leigh-Mallory and 34110 66 Squadron. The completion of 34110 was delayed due to proposals for a major modification to a standard two-cylinder design, without the chain-driven valve gear. In the event the loco entered traffic as Bulleid intended. The result of this delay was that the squadron crest for 66 Squadron was never made (although there is a drawing of it in The Book of the West Country/Battle of Britains (Irwell Press)), as the manufacturer had gone out-of-business during the intervening period.^[20] Thus 66 Squadron was the only BB Class member not to have a crest.

One highly recorded event occurred on 30 January 1965, when the un-rebuilt No.34051 Winston Churchill hauled the funeral train of its namesake from London's Waterloo station to his final resting place, close to Blenheim Palace in Oxfordshire.^[21]

[edit] Preserved 'Light Pacifics'

West Country Class 34007 Wadebridge 21C123 (34023) Blackmoor Vale 34092 City of Wells 34105 Swanage

Battle of Britain Class 34051 Winston Churchill 34067 Tangmere 34070 Manston 34072 257 Squadron 34073 249 Squadron 34081 92 Squadron

For location details of the preserved locomotives, see: List of SR West Country and Battle of Britain Class locomotives

[edit] Gallery

Another view of Un-rebuilt West Country Class 21C123 Blackmore Vale on the Bluebell Railway.

View of the boiler backplate on the footplate of 21C123 Blackmore Vale.

[edit] Footnotes

[edit] References

• Arlett, Mike: The Train Now Departing: Personal memories of the last days of steam (London: BBC Books, 1989) ISBN 0563206969

• Bulleids in Retrospect, Transport Video Publishing, Wheathampstead, Hertfordshire

• Bulleid, H. A. V.: Bulleid of the Southern (Hinckley: Ian Allan Publishing, 1977) ISBN 071100689X

• Burridge, Frank: Nameplates of the Big Four (Oxford Publishing Company: Oxford, 1975) ISBN 0902888439

• Creer, S. & Morrison, B.: The Power of the Bulleid Pacifics (Oxford Publishing Company: Oxford, 2001) ISBN 0860930823

• Day-Lewis, S.: Bulleid, Last Giant of Steam (1964),

• Derry, Richard: The Book of the West Country and Battle of Britain Pacifics (Irwell Press, 2004) ISBN 1903266238

• Fairclough, T. & Wills, A.: Southern Steam Locomotive Survey: Bulleid Light Pacifics (Kings Langley: Enterptise Transport Books Ltd., 1970) ISBN 0851532721

• Harvey, R. J.: Bulleid 4-6-2 Merchant Navy Class (Locomotives in Detail series volume 1) (Hinckley: Ian Allan Publishing, 2004), ISBN 0711030138

• Herring, Peter: Classic British Steam Locomotives (Abbeydale Press: London, 2000) Section "WC/BB Class" ISBN 1861470576

• Ian Allan ABC of British Railways Locomotives, winter 1958–59 edition

• The Railway Magazine (May, 2007), pp. 85

• Whitehouse, Patrick & Thomas, David St.John: SR 150: A Century and a Half of the Southern Railway (Newton Abbot: David and Charles, 2002)

[edit] Further reading

• Ian Allan ABC of British Railways Locomotives, winter 1955–56 edition

[edit] See also

• List of SR West Country and Battle of Britain Class locomotives

[edit] External links

• Southern E-group (1) – un-rebuilt 'Light Pacifics'
• Southern E-group (2) – rebuilt 'Light Pacifics'
• Diagram showing arrangement of the chain-driven valve gear
• Bulleid Society: WC/BB locomotive summary – Table showing key dates, mileages, running numbers, etc for all class members

{{SR Locomotives}} Category:4-6-2 locomotives West Country Category:Streamlined steam locomotives Category:West Country Category:Battle of Britain Category:1945 introductions Category:Locomotives of the Bodmin and Wenford Railway {{SR Locomotives}}

Category:4-6-2 locomotives Merchant Navy Category:Streamlined steam locomotives