Megan

Megan is a LMS Princess Royal who works on the mainline on The Island of Sodor.

## Technical Details:

Until the mid-1920s, the LMS had followed the Midland Railway's small engine policy, which meant that it had no locomotives of sufficient power for its expresses on the West Coast Main Line. These trains were entrusted to pairs of LMS/MR Midland Compound 4-4-0s between Glasgow and Carnforth, and a 4-6-0 locomotive of the LNWR Claughton Class, piloted by an LNWR George V 4-4-0, southwards to Euston station.

The Operating and Motive Power Departments of the LMS were satisfied with the small engine policy. However, in 1926 the Chief Mechanical Engineer, Henry Fowler, began the design of a compound Pacific express locomotive. The management of the LMS, faced with disagreement between the CME and the other departments, obtained a loan of a GWR Castle class locomotive, *Launceston Castle*, which was operated for one month between Euston and Carlisle.

Following the success of the Castle 4-6-0 in working on the LMS, a decision was taken to cancel Fowler's Pacific project, and to replace it with a 4-6-0 with three cylinders and a simple-expansion steam circuit. Because there was an urgent need for new express locomotives the LMS placed an order with the North British Locomotive Company of Glasgow for 50 engines. The North British, with its extensive drawing office and two works, possessed sufficient capacity to expedite the order within a year. The Derby drawing office and North British staff collaborated in designing the class, with the latter producing the working drawings. Fowler took little part in the design process, which was carried out by Herbert Chambers, Chief Draughtsman at Derby, and his staff. The LMS requested a set of drawings of the Castle class from the GWR, but did not receive them. Instead a set of drawings of the SR Lord Nelson Class were obtained, and used for the design of the firebox. The main features of the design followed existing Derby practice, with the cylinders and valve gear being derived from the Fowler 2-6-4T, also being designed at Derby at that time.

They were introduced without testing. Radford claims that the boiler owed much to the MR 0-10-0 Lickey Banker 'Big Bertha'. A further 20 were built by Derby Works.[*citation needed*]

They were initially named after regiments of the British Army, and after historical LNWR locomotives. Those with LNWR names were renamed in 1935 and 1936 with more names of regiments.From late 1931, after several forms of smoke deflectors were tried on various locomotives to stop drifting smoke obscuring the crew's forward vision, the straight sided smoke deflectors were added. These were later replaced by deflectors with angled top. From 1933 the class was taken off the top-link expresses, being superseded by the LMS Princess Royal Class and later the LMS Coronation Class pacifics.

### Rebuilding:

In 1942, the LMS rebuilt two LMS Jubilee Class locomotives with Type 2A boilers, but later turned to the parallel-boilered Royal Scots whose boilers and cylinders were life-expired, and whose smokeboxes were difficult to keep airtight. Between 1943 and 1955, the whole class was rebuilt to create the LMS Rebuilt Royal Scot Class. The rebuilds were quite substantial, requiring new boiler, frames and cylinders, but in most cases the original frame stretchers, wheels, cab and fittings were retained. The usual procedure was that as each locomotive arrived for rebuilding, it was stripped and the identity transferred to a fresh frameset prepared using the parts recovered from the locomotive that had previously been rebuilt. The new frames were slightly shorter than the originals. Thus, most rebuilt examples retained their own cab, wheels etc., but most of the frame stretchers, and other integral parts of the frame were from the previously rebuilt loco.

The new 'Rebuilt Scot' design was carried out under the auspices of William Stanier, who was then engaged on war work, so was actually undertaken by George Ivatt and E.S. Cox. Initially these too were built without smoke deflectors, but later acquired them.