The only remaining class 504 Electric Multiple Unit set still existing. The class 504 was a unique type of electric multiple unit that ran on 1,200 V DC third rail with side-contact current collection. All other mainline UK third rails have the electric "shoe" on top of the rail. The type was used only on the Bury Line between Manchester and Bury. They were built in 1959 at Wolverton Works, and the body was a standard type used for several electrification schemes of the time, but the high DC vol