The LNER Gresley A4 is one of the most iconic express locomotives in Great Britain, with its streamlined casing a classic symbol of the attitude towards speed and design in the 1930s, which 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, comfortable and more reliable.
Nigel Gresley, the LNER's Chief Mechanical Officer, travelled on the Fliegende Hamburger diesel locomotive in Germany and was impressed by its streamlining, although he realized it was only efficient at high speeds. Gresley was certain that a modified A3 Pacific, with streamlining, could haul greater loads than other locomotives at the same speed or faster and a series of trials were conducted to confirm the A3's suitability.
With the 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, higher boiler pressure and extension of the firebox to create a combustion chamber made them more efficient than the A3 as they consumed less coal and water- especially later on when they were also fitted with a Kylchap double chimney. This improved their free steaming capabilities further.
Their streamlined design not only made them capable of high speeds, but created an up draught of smoke, obscuring the driver's vision, a major problem on the new Class A4 engines. The story goes that during wind tunnel testing, after several unsuccessful efforts to get the smoke to lift clear, a thumbprint was inadvertently left on the clay model just behind the chimney. This succeeded in clearing the smoke and was incorporated into the final design.
4464 Bittern was rolled out of the Doncaster shed it was built in on the 18th December 1937 and entered LNER service shortly after. The locomotive would be renumbered to 60019 by BR, after its renumbering to 19 under the 1946 LNER renumbering scheme. Bittern was withdrawn on the 5th September 1966 and was destined for the scrapyard however was chosen for preservation after 60024 Kingfisher, originally selected, was found to have firebox problems.
Bittern officially entered preservation on the 12th September 1966. Bittern is currently at the One:One collection in Margate, awaiting overhaul which will take place once 60532 and 70000 are back on the mainline. In running preservation Bittern has carried the identities of some scrapped classmates such as 2509 Silver Link and 4492 Dominion of New Zealand.