The Brighton was almost paranoid about burning too much coal. Not surprising as they paid more for their coal than almost all other companies. This led to all sorts of heat recovery systems most of which led to heating the feed water in tanks and tenders, Normal injectors will not work with hot water so Brighton locos were often fitted with a feed water pump to get hot water into the boiler. E2s were so fitted and when they passed you and the pump was working there would be a distinct "clonk" with each stroke of the pump. Combined with the song of the Westinghouse pump on the other side a Brighton loco could be quite "musical".
Hope this explains everything if not come back.
CAT