This is "Bittern", a streamlined Class A4 Pacific (4-6-2) steam locomotive. The A4s were designed by Sir Nigel Gresley for the London and North Eastern Railway, and entered service from 1935 onward, hauling high-speed express passenger services.

"Bittern" herself entered service in 1937 and operated for about 30 years, first with the LNER and later with British Railways. After being withdrawn in 1966, "Bittern" was preserved but was, for serveral years, displayed as "Silver Link", the first A4 to enter service.

"Bittern" has recently been restored, resuming her own identity, and certified for main line operation. Her current role includes hauling special excursions for rail enthusiasts.