admired when it was exhibited at the 1900 Paris Exposition. The original S46 boiler had of heating surface, with a grate. The cylinders were 19 x 26 in. with flat valves placed below, operated by Stephenson's motion. The coupled wheels were in diameter. As built, the S46s were all fired by oil, using Holden's patented oil-burning apparatus which used a bed of fire brick, a supply of air fed from a pre-heater in the smokebox and steam-powered injectors which sprayed atomised oil onto the firebed. The firebox was heated, and steam for the injectors initially generated, by burning coal before switching to oil. The oil burnt was a waste product of the GER's gasworks that produced Pintsch gas for lighting its carriages. The GER had previously been fined for discharging this waste product into the River Lea, and the railway was thus able to fuel its oil-burning locomotives at little extra cost. The first ten of the D56 types were also built as oil-burners, but during the 1900s the increasing use of electric lighting in carriages and growing industrial demand for fuel oil meant that it was no longer cost-effective to use it as a locomotive fuel. Holden had always intended that his oil-burning system would allow engines so fitted to be easily converted to burn coal if required, and all the S46s and D56s had been switched to coal-burning by the end of 1911. When oil prices were low or coal was in short supply due to strike action some examples were re-fitted to burn oil for short periods but this was not done past 1927. Allen reports that Claud Hamiltons in their original state were capable of taking around 350 tons from Liverpool Street to North Walsham in under the booked time. No. 1882 with round-top boiler ran the in 156 min 60 sec. Even heavier trains were managed in the up direction: No. 1809 (Belpaire boiler) took 400 tons up in 157 minutes 24 seconds. The S46 design was substantially modified in later incarnations, particularly with the introduction of a larger superheated boiler on the H88 designed by Alfred John Hill. Most earlier members of the class were substantially modified by Hill or during the tenure of Sir Nigel Gresley as CME of the LNER from 1923. Two separate classes were also developed from the design of the Claud Hamilton; Holden's Class F48 (constructed between 1900 and