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LB&SCR I1 class
I1 class with modified chimney
Type and origin Power type Steam Designer D. E. Marsh Builder Brighton Works Build date 1906–1907 Total produced 20 Rebuild date 1925–1932
Specifications Configuration: ​  • Whyte 4-4-2T Gauge 4 ft 8+1⁄2 in (1,435 mm) standard gauge Driver dia. 5 ft 6 in (1.676 m) Loco weight 66 long tons 10 cwt (149,000 lb or 67.6 t) (74.6 short tons) Fuel type Coal Water cap. 1,839 or 1,924 imp gal (8,360 or 8,750 L; 2,209 or 2,311 US gal) Boiler pressure 170 psi (1.17 MPa) Cylinders Two, inside Cylinder size 17.5 in × 26 in (444 mm × 660 mm)
Performance figures Tractive effort 17,430 lbf (77.5 kN)
Career Class As built: I1 Rebuilt 1925–32: I1x Power class BR: 2P (I1x only) Numbers 595-604, 1-10 Nicknames Wankers Withdrawn 1944–1951 Disposition All scrapped

The LB&SCR I1 class was a class of 4-4-2 steam tank locomotives designed by D. E. Marsh for suburban passenger service on the London, Brighton and South Coast Railway.

This class was intended to haul secondary passenger trains,^[1] especially in the south London suburbs, and twenty locomotives were constructed by Brighton works between June 1906 and December 1907.^[1] The locomotives proved to be reliable but with disappointing performance in their original form, being poor steamers,^[2] but all of them passed to the Southern Railway in 1923.^[3] They reportedly gained the nickname "Wankers" due to the aforementioned steaming issues, but were also known as 'Wealden Tanks'.^[4]

Between 1925 and 1932 they were rebuilt by Richard Maunsell with spare boilers left over after the rebuilding of the B4 and I3 classes.^[5] The rebuilt engines were designated I1x class,^[3] and these new larger boilers greatly improved their performance.

Two worn-out members of the class were withdrawn by the Southern Railway in 1944 and 1946 respectively, but the remainder survived into British Railways (BR) ownership in 1948, although all had been withdrawn by July 1951 and none have been preserved.^[6]

The first ten were numbered 595–604 and the second ten were numbered 1–10.^[1] The Southern Railway initially added a "B" prefix to these numbers and later renumbered them 2595–2604 and 2001–2010. BR added 30000 to the numbers but it is believed that only 32005 actually carried its number.^[6]

• Bradley, D.L. (September 1974). The locomotives of the London Brighton and South Coast Railway, Part 3. London: RCTS.
• Dendy Marshall, C. F., History of the Southern Railway, Ian Allan 1988, page 270, ISBN 0-7110-0059-X

• Marsh I1/Maunsell I1x Class 4-4-2T Southern E-Group