Built in 1937 at the LNER's Doncaster Works, 'Bittern' was the twenty-fourth A4 Class locomotive.

'Bittern' started its working life-based at the Heaton Shed, Newcastle, and operated the famous Flying Scotsman train on the section between London King's Cross and Newcastle.

During the Second World War 'Bittern' was painted in black and was switched from hauling high-speed passengers to heavy freight trains. This was not what the A4s were designed for, and this coupled with poor maintenance took its toll causing them to fall into a poor condition by the close of the war.

'Bittern' is one of only three of the surviving A4 Class locomotives to still hold a mainline certificate which enables it to operate special rail excursions around the UK. Since being in preservation 'Bittern' has worn the identities of a number of its scrapped Classmates including 'Dominion of New Zealand' and 'Silver Link', the first ever A4 Class locomotive built.

As modelled here 'Bittern' has returned to its original livery of LNER Garter Blue, especially for the 'Mallard 75 - A4 Gathering' event at the National Railway Museum in York.