air-smoothed casing. In between, the casing was supported by channel-section steel crinolines (strengtheners used to maintain the shape) attached to the frames. The smokebox housed the five-nozzle Lemaître blastpipe arranged in a circle within a large-diameter chimney. Tender Bulleid designed a new tender which could carry 5 tons (5.1 t) of coal on a six-wheel chassis. It featured BFB wheels and streamlined panels, or "raves", that gave the top of the tender a similar cross-sectional outline to the carriages hauled by the locomotive. The water tank was of welded sheet construction to save weight, and the tender was fitted with vacuum braking equipment of a clasp-type similar to that used on the locomotive. Three train-brake vacuum reservoirs of cylindrical construction were grouped on the tank top, behind the coal space. Unusually for a British locomotive, two extra water filler caps were incorporated into the tender front, for access from the footplate. The original tender design proved to be inadequately braced and subject to serious leakage if even slightly damaged, or when water surges caused the welded joints to split. The problem was not solved until 1944 when additional baffling was fitted. Other innovations Electric lighting was also provided on both the locomotive and the footplate, supplied by a steam-powered generator fitted below the footplate. The gauges were lit by ultra-violet light. This enabled clearer night-time vision of the boiler steam pressure gauge and the brake pipe vacuum gauge, whilst eliminating dazzle, making it easier for the crew to see signals along the track. Close attention was also paid to the ergonomics of the driving cab, which was designed with the controls required for operation grouped according to the needs of both fireman and driver, thus promoting safe operation. As an aid to the fireman, a steam-operated treadle was provided that used steam pressure to open the firehole doors (where the coal is shovelled into the firebox). The footplate was entirely enclosed, improving crew working conditions in winter. Construction The Southern Railway placed an order for ten of the new locomotives to be built at Eastleigh Works, although the boilers had to be supplied from private industry and the tenders were built at Ashford. The prototype was completed in February 1941, numbered 21C1, and named Channel Packet at a ceremony at Eastleigh works on 10 March 1941. It underwent extensive trials and minor modifications before joining Southern Railway stock 4 June