LSWR A12 class
The A12 locomotives of the London and South Western Railway were built between the years 1887 and 1895 to the design of William Adams. Ninety of the locomotives were built, fifty at Nine Elms Works and forty by Neilson and Company, although the latter together with the final twenty from Nine Elms were officially known as the O4 class. They were unusual for their time, with a wheel arrangement of 0-4-2. This arrangement was used by few of the other railway companies and never proved popular. They bore the nickname "Jubilees", because the first batch appeared in the Golden Jubilee of Queen Victoria's reign.
The class were intended for mixed traffic role. Unlike many other British railways, the LSWR had little heavy freight or mineral traffic. The A12s were designed for a dual role of non-express main line passenger services and fast goods, parcels and perishables traffic. Their size, power and design barred them from the fastest express and mail trains on the LSWR, but made them ideal for heavier, slower passenger trains such as holiday and excursion traffic between London and Bournemouth, Poole and the Dorset coast and military trains between the army camps in London and northern Hampshire and the Channel ports, which were an important traffic for the LSWR. The A12s were well-suited to running goods trains of livestock, fruit and milk, on the West of England line between London and Exeter and parcels and express freight going between London and Southampton docks. The class also found a role working secondary cross-country passenger services west of Salisbury, on the route to Plymouth and on rural lines in Hampshire.
History
The 90 members of the class were built in batches, as shown in the following table.| Year | Order | Builder | Quantity | LSWR numbers | Notes |
| 1887 | A12 | LSWR Nine Elms | 10 | 527–536 | |
| 1888 | E1 | LSWR Nine Elms | 10 | 537–546 | |
| 1889 | M2 | LSWR Nine Elms | 10 | 547–556 | |
| 1893–94 | O4 | LSWR Nine Elms | 10 | 597–606 | |
| 1892–93 | — | Neilson & Co. 4506–4545 | 40 | 607–646 | |
| 1894–95 | K6 | LSWR Nine Elms | 10 | 647–656 |
All 90 passed to the Southern Railway in 1923, following the introduction of the Grouping Act.
Withdrawal
Withdrawals started in 1928, with four of the class surviving to Nationalisation. The four operated by British Railways were all withdrawn in its first year, excluding DS3191 which was used for steam supply at Eastleigh Works and lasted until 1951. No members of the class have been preserved.| Year | Quantity in service at start of year | Quantity withdrawn | Locomotive numbers | Notes |
| 1928 | 90 | 6 | E529, E535, E542, E548, E552, E553 | |
| 1929 | 84 | 13 | E528, E531–E533, E536, E537, E540, E543, E544, E547, E549, E550, E556 | |
| 1930 | 71 | 3 | E527, E539, E546 | |
| 1931 | 68 | 6 | E530, E534, E538, E541, E545, E554 | |
| 1932 | 62 | 6 | 551, 607, 608, 610, 653, 656 | |
| 1933 | 56 | 9 | 602, 604, 626, 631, 633, 639, 645, 647, 651 | |
| 1934 | 47 | 1 | 601 | |
| 1935 | 46 | 3 | 603, 621, 635 | |
| 1936 | 43 | 4 | 605, 616, 622, 655 | |
| 1937 | 39 | 4 | 611, 619, 632, 640 | |
| 1938 | 35 | 3 | 617, 628, 650 | |
| 1939 | 32 | 1 | 646 | 613, 620, 624, 625, 629, 642, 644 withdrawn and then reinstated |
| 1944 | 31 | 1 | 555 | |
| 1946 | 30 | 12 | 599, 600, 606, 612, 613, 615, 620, 623, 637, 641, 644, 649 | 612 transferred to Departmental stock as 3191S, later BR DS3191; scrapped 1951 |
| 1947 | 18 | 14 | 597, 598, 609, 614, 624, 625, 630, 634, 638, 642, 643, 648, 652, 654 | |
| 1948 | 4 | 4 | 618, 627, 629, 636 |