The 1930s saw increased competition to the railways from road and air travel. The LNER Board knew that they had to make travel between the major cities faster, more comfortable and more reliable. High speed diesel services were starting to make an impact abroad. For example, in 1933, the German State Railways diesel-electric Fliegende Hamburger entered service. It could run for extended periods at 85mph.
Nigel Gresley, the LNER’s Chief Mechanical Officer, travelled on the Fliegende Hamburger. He was impressed by its streamlining, although he realised it was only efficient at high speeds.
Gresley was certain that a modified A3 Pacific, with streamlining, could haul greater loads than the German or US locomotives, at the same speed or faster. With trials successfully completed, the LNER Board gave Gresley the go-ahead to create the “Silver Jubilee” streamlined trains, the first of the new streamlined A4s.
The streamlining of the A4s’ steam circuit, their higher boiler pressure and the extension of the firebox to create a combustion chamber, made them more efficient than the A3 as they consumed less coal and water. Their streamlined design not only made them capable of high speeds, but created an updraught of smoke, avoiding the obscuring of the driver’s vision that was such a major problem on the Class A4 engines. The story goes that during wind tunnel testing, they unsuccessfully tried to clear the smoke. Inadvertently, somebody left a thumbprint on the clay model, just behind the chimney. This succeeded in clearing the smoke and so they incorporated it into the final design.
During their construction period between 1935 and 1938, these engines totalled 35 built. They spent their working lives hauling express passenger services from King’s Cross to Edinburgh, via York and Newcastle. The last A4 service retired in 1966.
In July 1938, whilst travelling at Stoke Bank (Rutland) on the East Coast Mainline, the Mallard broke the speed record. Recorded as travelling at 126mph, it snatched the record from the German railway by a mere 1.5 mph – a record that still stands to this very day.
Mallard is now part of the National Collection and preserved at the National Railway Museum in York.
