hammerblow and exacerbated by irregularities in track-work. This caused excessive stress to the axleboxes and poor riding characteristics on the footplate. Despite this, the class benefited from an excellent maintenance regime. Maunsell's replacement Oliver Bulleid believed that there was little need to improve draughting on this series. However, reports of poor steaming with No. 792 Sir Hervis de Revel gave him an opportunity to trial a Lemaître multiple-jet blastpipe and wide-diameter chimney on a Maunsell Arthur in 1940. This did not enhance performance to the extent of No. 755 The Red Knight. Under British Railways ownership, the locomotive was re-fitted with the Maunsell chimney in March 1952 with no further problems reported. In another wartime experiment, Bulleid fitted No. 783 Sir Gillemere with three thin "stovepipe" chimneys in November 1940. These were set in a triangular formation to reduce visibility of exhaust from the air in response to attacks made by low-flying aircraft on Southern Railway trains. The "stovepipes" were reduced to two, producing a fierce exhaust blast that dislodged soot inside tunnels and under bridges. The experiment was discontinued in February 1941 and the locomotive re-fitted with a Maunsell King Arthur chimney. The last experiment was with spark-arresting equipment in response to lineside fires caused by poor quality coal. Nos. 784 Sir Nerovens and 788 Sir Urre of the Mount were fitted with new wide-diameter chimneys in late 1947. Test-trains showed mixed results and the trials were stopped in 1951 after improvements in coal quality and the fitting of internal smokebox spark-arrestors. Withdrawal The detail variations across the class meant the "Urie N15s" were placed into store over the winters of 1949 and 1952. The Maunsell King Arthur examples were easier to maintain, and the large number of modern Bulleid Pacific and British Railways Standard classes were able to undertake similar duties. The "Urie N15s" were brought into service during the summer months, although their deteriorating condition was demonstrated when No. 30754 The Green Knight was withdrawn with cracked frames in 1953. The slow running-down of the "Urie N15s" continued between 1955–1957, and several were stored prior to withdrawal. The last three were withdrawn from Basingstoke shed, with No. 30738 "King Pellinore" the final example to cease operation in March 1958. All were broken up for scrap, though their names were given to 20 BR Standard class 5 locomotives allocated to the Southern Region between 1959–1962. The Maunsell King