LSWR N15 class

Infobox Locomotive
name = LSWR N15 class / SR King Arthur class Swift, pp. 84–91]

caption = Preserved 30777 "Sir Lamiel" is part of the National Collection, and is currently operating in British Railways Brunswick Green livery.
designer = Robert Urie
Richard Maunsell "(redesign)"
Oliver Bulleid "(modifications)"
builder = SR Eastleigh Works (44)
North British (30)
builddate = 1919–1926
totalproduction = 74
whytetype = 4-6-0
gauge = RailGauge|ussg|lk=on
leadingsize = convert|3|ft|1|in|m
driversize = convert|6|ft|7|in|m
length = convert|66|ft|5.75|in|m
weight =80 tons 19 cwt (82.2 tonnes)
"(Nos. 448–452 and 763–792)"
79 tons 18 cwt (81.2 tonnes)
"(Nos. 453–457)"
81 tons 17 cwt (83.2 tonnes)
"(Nos. 793–806)"
fueltype = coal

"(Urie outside-frame bogie tender)"
"(Urie outside-frame bogie tender)"
"(Maunsell bogie tender)"
"(Drummond bogie tender)"
"(Six-wheel tender)"
cylindercount = 2
cylindersize =22in × 28in (560mm × 710mm)
"(Urie batch – as built)"
21in × 28in (530mm × 710mm)
"(Urie batch – as modified)"
20.5in × 28in (520mm × 710mm)
"(Eastleigh/Scotch batches )"
boilerpressure = convert|180|psi|MPa|2|abbr=on|lk=on
"(Urie batch)"
"(Eastleigh/Scotch batches)"
tractiveeffort = convert|23900|lbf|kN|2|lk=on|abbr=on
"(Maunsell batch)"
railroad=London & South Western Railway,
Southern Railway (Great Britain),
British Railways (Southern Region)
locale=Great Britain
railroadclass="LSWR:" N15
"SR:" King Arthur
"BR:" 5P
preservedunits=One, No. 777

The LSWR N15 class was a British 2-cylinder 4-6-0 express passenger steam locomotive designed by Robert W. Urie. The class has a complex build history spanning several years of construction from 1919 to 1926. The first examples were constructed for the London and South Western Railway (LSWR), where they hauled heavy express trains to the south coast ports and further west to Exeter.

Following the Grouping of railway companies in 1923, the LSWR became part of the Southern Railway and its publicity department gave the locomotives names associated with Arthurian legend. [ Nock, p. 241] The Chief Mechanical Engineer (CME) of the newly-formed company, Richard Maunsell, increased the King Arthur class strength to 74 locomotives. Maunsell incorporated several improvements, notably to the steam circuit.

The new locomotives were built in batches at Eastleigh and Glasgow, leading to the nicknames of "Eastleigh Arthurs" and "Scotch Arthurs" in service. Maunsell's successor, Oliver Bulleid, further improved performance by altering exhaust arrangements. The locomotives continued operating with British Railways until the end of 1962. One example, 30777 "Sir Lamiel", is preserved as part of the National Collection and can be seen on mainline railtours.


The management of the LSWR saw the need for a modern, standard express passenger locomotive to work from London to the south-west of England, hauling the heavy boat trains to the south coast ports of Portsmouth, Weymouth and Southampton. Swift, p. 9] Robert Urie found that his H15 4-6-0 showed considerable speed potential on the western section of the LSWR from Basingstoke westwards, [Nock, pp. 142–144 ] and could be developed into a new class of 4-6-0 express passenger locomotives with convert|6|ft|7|in|m|abbr=on driving wheels. Swift,p. 92]

Design details and construction history

Urie N15s

The first locomotives, known as the "Urie N15s", were built in two 10-engine batches by the London and South Western Railway's Eastleigh Works between 1918–19 and 1922–23. Swift, p. 14] The first batch was a direct development of Urie's H15 locomotive design, incorporating a Drummond-style cab, Urie's "stovepipe" chimney and Urie's new version of Drummond's bogie tender with outside plate frames over the wheels. The chimney was found to cause draughting problems in service which were not resolved until they entered Southern Railway service. During an intensification of the LSWR timetables, the locomotives gained a reputation for being poor steamers on long runs, as crews reported steadily falling steam pressure.Clarke: "Steam World" (April 2008), p. 49] Beginning in 1928, all but one had their cylinder diameter reduced from convert|22|in|mm to convert|21|in|mm, improving efficiency as less steam was required to move the smaller piston. [Ian Allan Abc 1956 "N15"]

Modifications, naming and Maunsell's "Eastleigh" Arthurs

At the "Grouping" of 1923, the LSWR became part of the new Southern Railway, whose Chief Mechanical Engineer was Richard Maunsell. Maunsell planned to introduce his own designs into the express passenger category of steam locomotives, one of which was to become the future Lord Nelson Class. However, there was a pressing need to maintain existing services, necessitating the modification of weaker aspects of Urie's original N15 design as an interim solution. Herring, pp. 110–111] A larger diameter chimney and blastpipe were two of Maunsell's improvements to the steam circuit, which resulted in a fast, free-steaming locomotive. Swift, p. 38] Beginning in 1925 a new series was built at Eastleigh with improved valve events (the timing of valve movements with the piston), increased boiler pressure (convert|200|psi|MPa|2|abbr=on) and reduced cylinder diameter (convert|20.5|in|mm). The locomotives were equipped with Maunsell's smaller version of the Urie 8-wheel bogie tender with a capacity of convert|5000|impgal of water and 5 tons (5.1 tonnes) of coal. The modifications were sufficient to achieve extended running on the Southern's western section, where there were no water troughs to replenish water in the tender without stopping.

Maunsell's projected design of express passenger locomotive was not ready in time for the summer timetable of 1925, so a third batch of 10 locomotives was ordered for construction at Eastleigh in 1925. This batch used the tenders and running numbers of the withdrawn Drummond LSWR G14 and P14 classes, and differed from the original Urie batch in their use of higher boiler pressure and smaller cylinders.Haresnape, Section "N15 class"]

While the third batch was under construction, the Southern Railway decided to give names to all express passenger locomotives. Because of the Southern's association with the West of England, the N15 class was named after characters and places associated with the legend of King Arthur. The first-completed G14 replacement, no. E453, was given the first name and christened "King Arthur". The Urie N15s were also given names connected with Arthurian legend and were referred to as "Urie Arthurs"; the Maunsell batch of N15s were nicknamed the "Eastleigh Arthurs". When Maunsell was told of the decision to name the locomotives, he replied: "Tell [Sir Herbert Walker] I have no objection, but I warn you, it won't make any difference to the working of the engines". [ Nock, p. 241]

"Scotch" Arthurs and Bulleid's modifications

At the same time as the construction of the "Eastleigh Arthurs", Maunsell ordered a further batch of 20 locomotives from the North British Locomotive Company in 1924 for delivery in 1925. Swift, pp. 19–25] This order was increased to 30 locomotives, and their construction in Glasgow gained them the "Scotch Arthurs" nickname in service. These were built to the Southern's new composite loading gauge and differed from previous batches in having the Ashford-style cab, which was usually fitted to LBSCR locomotives. Unlike the Drummond cab, the Ashford-style cab was of an all-steel construction and had a roof that was flush with the cab sides. It was inspired by the standard cab developed in 1904 by R. M. Deeley for the Midland Railway, and was one of a number of Midland features introduced by Maunsell's chief draughtsman James Clayton, who transferred to Ashford Works in 1914 from the Midland Railway. Clarke: "Steam World" (April 2008), p. 49] Variants of this cab became standard for all new Southern Railway locomotives and converted tank engines.

A final batch of 14 engines was ordered for use on the central section of the Southern Railway, the former LBSCR network, being built at Eastleigh in 1926. These were equipped with a smaller capacity 6-wheel, convert|3500|impgal|l|abbr=on tender which allowed these locomotives to be turned on the shorter turntables found in this part of the Southern Railway network.

In 1926 the N15 class became the first in Britain equipped with smoke deflectors, with several designs tested. Swift, p. 32] Further attempts to improve draughting and smoke deflection were undertaken when Oliver Bulleid was appointed CME in 1937, five locomotives were modified with Lemaître's multiple-jet blastpipe and wide-diameter chimney, resulting in improvements in performance that enabled these locomotives to operate more efficiently. [ Bulleid, H.A.V. – for information on Oliver Bulleid's modifications]

Operational details

:"For class details and current status of the preserved locomotive, see: List of King Arthur class locomotives"

The locomotives were well-received by their crews and were noted for their ability to "do the job", and for putting in many years' reliable, although unspectacular, service.Banks, p. 50] However, a common criticism from locomotive crews concerned the exposed nature of the cab in bad weather, which necessitated the installation of a tarpaulin sheet over the rear of the cab and the front of the tender. Another criticism was the lack of stability at high speeds, which was commented-upon by the London and North Eastern Railway's CME, Sir Nigel Gresley when they were used on the former Great Northern main line for performance trials against the LNER Class A1s during the 1920s. Instability at speed is a frequent issue with two-cylinder locomotives, where there is a greater tendency to "waddle" along the track, a motion which is perpetuated by the piston movement. The opportunity for staging these trials had presented itself with the visit of number 449 "Sir Torre" to the Darlington Railway Centenary celebrations in July 1925.Casserley, p. 77 ]

The class was found in most areas of the British Railways Southern Region network on medium-length expresses and stopping trains on the ex-LSWR mainline, though the detail variations across the class meant that the Urie Arthurs began to be withdrawn as early as 1953 for reasons of standardisation. Clarke: "Steam World" (April 2008), p. 48] The first withdrawal, 30754 "The Green Knight", began the slow running-down of the class, but because so many engines were constructed, they outlasted the newer Lord Nelson class by one month. The last withdrawal was 30770 "Sir Prianius" from Basingstoke Shed in November 1962.

The number of batches constructed at different locations and times inevitably meant detail differences between members of the class. No. 755 was unique in having a different cylinder bore to the rest of the class at 22 inch (559 mm). Clarke: "Steam World" (April 2008), p. 50] Further detail differences comprised weight variation: 80 tons 19 cwt (82.2 t) for Nos. 448–452 and 763–792, 79 tons 18 cwt for Nos 453–457, and 81 tons 17 cwt (82.1 t) for Nos. 793–806.Bradley, N15 class details]


Because of the relatively early withdrawal of the class by the end of 1962, only one was saved for posterity, and as of 2008, the National Collection's 30777 "Sir Lamiel" can be seen on the railway network hauling mainline railtours. "Sir Lamiel" was named after a character in Thomas Malory's "Le Morte d'Arthur", Sir Lamiel of Cardiff.Burridge, Section "King Arthur class Names"]

Livery and numbering

LSWR and Southern Railway

Under LSWR ownership, the Urie Arthurs were painted in the LSWR Sage Green livery for passenger locomotives. The bodywork was painted green, with black and white lining decorating the borders of the panels. The lettering was in gilt: the initials "LSWR" located on the side of the tender, the locomotive number on the cabside. Swift, p. 50]

The first Southern livery continued that of the LSWR, though with the number displayed on the tender. However beginning in 1925, a darker olive-green was substituted, and the entire class was repainted. Wheels were green with black tyres, while the painted cabside numerals were replaced by a cast oval plate with "Southern Railway" around the edge and the number located in the centre. Primrose yellow transfers, showing "Southern" and the locomotive number, were placed on the tender tank.

In 1939, after Bulleid's appointment as CME, the locomotives were subjected to livery experimentation. "Southern" remained on the tender, though the number was relocated on the cabside, both were "sunshine yellow". Several variations of the Maunsell Green and Bulleid Malachite Green liveries were tried with black, white/black and yellow lining, some sporting a green panel on the smoke deflectors. Swift, p. 56] However from 1942 to 1946, during the Second World War, the class was turned out in unlined-black livery with green-shaded sunshine yellow lettering. The final Southern livery used from 1946 reverted to Malachite Green, with yellow-and-black lining, and sunshine yellow lettering. However, some of the class (numbers 792 and 800, "Sir Brian" and "Sir Persant") did not receive this livery. Swift, p. 64]

Post-1948 (nationalisation)

British Railways gave the class the power classification of 5P after nationalisation in 1948. Swift, p. 65] For the first 18 months the locomotives sported a transitional livery: Southern Malachite Green livery with "British Railways" on the tender in sunshine yellow lettering. As each member of the class became due for a heavy general overhaul, they were released in the British Railways express passenger livery of Brunswick green with orange and black lining. Initially, the British Railways "Cycling Lion" crest was located on the tender, replaced from the mid-1950s by the later "Ferret and Dartboard" crest.

Numbering was originally that of the Southern Railway, though an 'S' prefix was added to denote a pre-nationalisation locomotive, so that number 448 would become s448. As each locomotive became due for overhaul and received its new livery, the numbering was changed to the British Railways standard numbering system, in the series 30448–30457 for the first ten and 30736–30806 for the rest.Ian Allan Abc 1958–59 "N15"]



* Banks, Chris: "BR Locomotives 1955" (Oxford Publishing Company: Oxford, 2001), ISBN 0860935604
* Bradley, D. L.: "LSWR Locomotives - the Urie classes" (Wild Swan Publications, 1987), ISBN 090686755X
* Bulleid, H. A. V.: "Bulleid of the Southern" (Ian Allan Publishing: Hinckley, 1979)
* Burridge, Frank: "Nameplates of the Big Four" (Oxford Publishing Company: Oxford, 1975) ISBN 0-90288-843-9
* Clarke, Jeremy: 'The Locomotives of R. E. L. Maunsell' ("Steam World": 250, April 2008)
* Haresnape, Brian: "Maunsell Locomotives - a pictorial history" (Ian Allan Ltd, 1977), ISBN 0711007438
* Herring, Peter: "Classic British Steam Locomotives" (Abbeydale Press: London, 2000) Section "King Arthur & Lord Nelson Classes" ISBN 1-86147-057-6
* "Ian Allan ABC of British Railways Locomotives", 1956 edition (Hinckley: Ian Allan Publishing, 1959)
* "Ian Allan ABC of British Railways Locomotives", winter 1958–59 edition (Hinckley: Ian Allan Publishing, 1956)
* Nock, O.S.: "British Locomotives of the 20th Century", Vol. 1 (Book Club Associates, 1983)
* Swift, Peter: "Maunsell 4-6-0 King Arthur Class (Locomotives in Detail series volume 4)" (Hinckley: Ian Allan Publishing, 2006), ISBN 0711030863

See also

* List of King Arthur class locomotives

External links

* [ SEMG gallery article on the N15s]

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