In 1936,
Nigel Gresley, the chief mechanical engineer of the LNER, ordered a new batch of six
4-6-2 "Pacific"
Class A4 engines to be built at
Doncaster Works. The A4s were known for their distinct streamlined and aerodynamic design and designed for hauling long-distance express passenger services at high speeds. The first batch comprised four locomotives which entered service in 1935 and had "Silver" in their names as they were to haul the non-stop
Silver Jubilee service between London King's Cross and Newcastle. The six new A4s were each named after a bird, influenced by Gresley's fondness for breeding wild birds, and incorporated some modifications to maximise the possibilities of the original streamlined design. Upon arrival at London King's Cross, driver Duddington and inspector Sid Jenkins were quoted as saying that they thought a speed of would have been possible if the train did not need to slow for a set of junctions at Essendine. There was also a permanent speed restriction of just north of Grantham station, which slowed the train as they sought to build up maximum speed for the descent of Stoke Bank. The A4 class previously had problems with the
big end bearing for the middle cylinder, so the big end was fitted with a "stink bomb" of
aniseed oil which would be released if the bearing overheated. After attaining the record speed, the middle big end did overheat and the crew reduced speed, running at onwards to Peterborough, after which
Mallard was sent to
Doncaster Works for repair. This had been foreseen by the publicity department, who had many pictures taken for the press, in case
Mallard did not make it back to Kings Cross. The (Edwardian period)
Ivatt Atlantic that replaced
Mallard at Peterborough was only just in sight when the head of publicity started handing out the pictures.
Mallard topped Stoke Bank at and accelerated downhill. The speeds at the end of each from the summit were recorded as: , , , , , and ; half-mile (800 m) readings after that gave 120, 122, 123, 124 and finally 125 mph (194, 197, 198, 200 and 201 km/h). However, the dynamometer car tracks the current speed every half second on a paper roll moving for every mile travelled. Speeds could be calculated by measuring the distance between the timing marks. Immediately after the run staff in the dynamometer car calculated the speed over five second intervals, finding a maximum of . Although was seen for a single second, Gresley would not accept this as a reliable measurement and was the figure published. Gresley planned to have another attempt in September 1939, but this was prevented by the outbreak of World War II. In 1948, plaques proposed and designed by Harry Underwood, a headmaster and keen steam enthusiast, were fixed onto the locomotive which stated , and this became the generally accepted speed. Despite this, some writers have commented on the implausibility of the rapid changes in speed. A recent analysis has claimed that the paper roll was not moving at a constant rate, and the peaks and troughs in the speed curve resulting in claims of held for 5 seconds and for one second were just a result of this measuring inaccuracy. It concluded that a verifiable maximum speed was a sustained for almost a mile. On 3 July 2013, the 75th anniversary of the speed record, all six surviving A4 locomotives were brought together at the National Railway Museum.
Rival claims Mallards record has never been officially exceeded by a steam locomotive, although a German
DRG Class 05 reached in 1936 on a stretch of track that is flat, unlike Stoke Bank, which is slightly downhill. However, the Class 05 hauled a four-coach train of 197 tons, whereas
Mallards seven-coach train weighed 240 tons. Several unattested speed claims are tied to the US
Pennsylvania Railroad and their various
duplex locomotive classes. The
S1 class during its lifetime was claimed to having reached between and . Speed claims tied to the
T1 class state the locomotive reached speeds up to . Project
Pennsylvania Railroad 5550 was constructing a brand-new T1, and stated their desire to test the locomotive when completed to see if it could claim the speed record from
Mallard. In 2025 completion date of the project, started in 2013, was estimated at 2030.
1948 Locomotive Exchange Trials In 1948, shortly after the formation of
British Railways, the decision was taken to test locomotives from all of the former 'Big Four' companies to find the best attributes of speed, power and efficiency with coal and water. There were two ways of testing and comparing locomotives: either at the
Rugby Locomotive Testing Station, which was not ready until late 1948, or by testing in the field. The results of the
1948 Locomotive Exchange Trials would be used to help design the British Railways
Standard locomotives. The express passenger locomotive designs which would be compared were:
London Midland Region (former
LMS)
Princess Coronation class,
Eastern Region (former
LNER)
Class A4,
Southern Region (former
Southern)
Merchant Navy class and
Western Region (former
GWR)
King class. Three Gresley A4 locomotives were chosen to represent the Eastern Region: E22
Mallard,
60033 Seagull and
60034 Lord Faringdon. All of the locomotives had the Kylchap double blastpipe chimney arrangement and were fresh from Doncaster works.
Mallard had emerged from Doncaster with a fresh coat of post-war garter blue livery, stainless steel numbers 22 with a small 'E' painted above them (for Eastern region), new boiler (its fourth), and third tender of its career. E22
Mallard was used on 8 June 1948 on the
London Waterloo to
Exeter route. Driver Marrable took the famous A4 with a load of 481 tons tare, 505 tons full, the same that had been used on the previous trip by
35018 British India Line.
Mallard reached
Clapham Junction in 6 minutes 57 seconds and Woking in 28 minutes 47 seconds. At Hook there were adverse signals, causing
Mallard to slow to a crawl. Even so,
Salisbury was reached in 108 minutes and 28 seconds. Despite the signals earlier, the train was only minutes late. The net time was 95.5 minutes.
Mallard failed after this trial and 60033
Seagull took over. On 10 June
Seagull achieved the run in 96 minutes 22 seconds, but had departed 3 minutes late, meaning
Seagull had arrived with the same load 3.5 minutes early.
Mallard returned to the Waterloo-Exeter line for a Locomotive Club of Great Britain (LCGB) railtour on 24 February 1963.
The Elizabethan '' in Darlington in 1961 The
Elizabethan Express was a flagship express that ran non-stop over the between
London King's Cross and
Edinburgh Waverley from 1953 to the mid-1960s. Until September 1961 it was steam-hauled. In its day it was the longest non-stop run in the world. Two crews were needed for the six-and-a-half-hour run. They were able to change over mid-journey by using a
corridor tender. Only 22 locomotives including
Mallard had such a tender. In December 1961,
Mallard hauled the final steam-hauled northbound
Elizabethan train. ==Preservation==