The Record Breakers…


Fireman Thomas Bray, Driver Joseph Duddington, Inspector S. Jenkins after their record breaking run 70 years ago.

The London and North Eastern Railway’s pacifics were probably the most famous of the LNER locomotives, and the A4 pacific, Mallard, vies with A1[1] pacific Flying Scotsman, for the title of the most famous of all. On 30 November 1934, running a light test train, Flying Scotsman became the first steam locomotive to be officially recorded at 100 mph (160.9 km/h). On 3 July 1938 ago Mallard raised the world rail speed record to 126 mph (203) km/h). It is a performance which no steam locomotive has ever been able to surpass[2].

Mallard’s record run was made with a six car streamline set plus a dynamometer car, with a total tare of 240 tons. This locomotive was chosen because it was one of four engines fitted with Kylchap exhaust. These engines had better steaming and freer running qualities than the A4’s fitted with standard blastpipe and chimney. Mallard was also a new engine that had been ‘run in’ during three months of service prior to the speed run.

The train started to the north of Grantham and headed south along the LNER route. As it passed the station it was travelling at a modest 24 mph (39 km/h) and after two and a half miles, at a slight upwards incline, the train had accelerated to 59.75 mph (96 km/h). One and a half miles later the speed had increased to 69 mph (111 km/h) and up the final one and a half miles of incline, through the tunnel to Stoke box, it reached 74.5 (120 km/h) mph as the summit box was passed.

Now, with a descending gradient of between 1:178 and 1:200, the way was clear for Mallard and her crew to go for the record. From milepost 100, the speed was 87.5 mph (141 km/h); at milepost 93, it was 119 mph (191.5); around milepost 90, 125 mph had been reached (201.2 km/h); and the dynamometer record, for a very short distance, showed a maximum of 126 mph (202.8 km/h). At this point the six foot eight inch driving wheels were doing more than 500 revolutions a minute.

In the 1930s, the British railway companies were facing increased competition from road and air travel. It was clear that services between the major cities had to be faster, more reliable, and more comfortable. Sir Nigel Gresley, the Chief Mechanical Engineer of the LNER, was well aware of this. The A3 pacifics, a development of his A1s, were fast and efficient, and he began researching streamlining to see whether it would be feasible to produce an improved versions of the A3 to compete with other streamlined trains, such as the German State Railways diesel-electric Fliegende Hamburger and the US Burlington Zephyr, both of which were attracting publicity for their high speed services.

What Gresley eventually came up with, after long periods of wind tunnel testing and internal reworkings, was the all new class A4. Along with the distinctive new shape Gresley had made some improvements under the bonnet. All of the steam passages were streamlined, along with the boiler pressure being increased from 220psi to 250psi. Also, the cylinders were decreased slightly in size so that the valve diameters could be increased to nine inches. A demonstration run from Kings Cross to Grantham on 27 September, 1935, where the train touched 112.5mph (181 km/h). In fact, because of the smoothness of the footplate, the locomotive’s crew only thought they were travelling at 90 mph (145 km/h), and it wasn’t until Gresley squeezed though the corridor tender to inform them that some of the passengers were becoming nervous that they slowed down!

Friendly competition ensued between the rival companies, particularly the LMS and LNER. Higher and higher speeds were being reached by the drivers despite often direct breaches of safety regulations, but eventually, after stern warnings from railway directors, the heads of both companies struck a gentlemen’s agreement that they would no longer put speed before passenger comfort and safety. When this agreement was reached it was one of the LMS streamlined pacifics, Coronation that held the record at 114 mph, but Gresley, was determined to attain the high speed record with one of his locomotives, and it was under the cover of regulation brake tests that he had his chance, partly because of the lack of passengers on board and partly because of the recording equipment in the dynamometer car that would be able to authenticate a record should one be achieved.

The record run started from Barkston triangle, running southbound. Mallard pulled the train over Stoke Summit at 75 mph (121 km/h) and began to accelerate downhill. The speeds at the end of each mile (1.6 km) from the summit were recorded at: 87½, 96½, 104, 107, 111½, 116 and 119 mph (141, 155, 167, 172, 179, 187 and 192 km/h); half-mile (800 m) readings after that gave 120¾, 122½, 123, 124¼ (194, 197, 198, 200 Km/h) and finally 125[3] mph (201 km/h), with a peak at 125.88 mph (202.6 km/h) recorded by the dynamometer car for a few seconds. After the locomotive slowed down due to a speed restriction, the inside big end showed sign of overheating and the engine had to run light back to Doncaster for repair.

But the deed had been done, Mallard‘s speed had exceeded that not only of the LMS Coronation, but of all other steam locomotives in the world whose high speed performances were properly authenticated and recorded, and since that time no steam locomotive has ever travelled faster. Mallard, after being restored to main line running condition, was retired in 1987 and can now be seen at the United Kingdom’s National Railway Museum in York.


  1. Flying Scotsman was subsequently rebuilt as an A3.
  2. While there are claims that some steam locomotives may have run faster there are no independently verified records.
  3. Gresley didn’t count the momentary surge and would only refer to Mallard having reached 125 mph (201 km/h). He believed that, fine-tuned, the locomotive should be capable of 130 mph (209 km/h), but the advent of WW II prevented him from making another attempt at the record.


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