This locomotive was one of three built in 1952 by the Hunslet Engine Company for Robert Hudson (explaining the unusual manufacturers' title which appears prominently, cast into the locomotive's radiator frontage). It was built to run in a sand and gravel pit in Twickenham and did so until closure, after which the three were put up for sale. Along with works No. 4352 the locomotive was purchased by Doddington Park in Chipping Sodbury where a pleasure ground had been established. It was at this time that the locomotive acquired a "steam outline" structure. This consisted of a sheet metal half-cab with oval windows, false dome and chimney. The exhaust from the engine which had previously been directed beneath the frames was re-routed to be shot from this new chimney to give the appearance that the engine was "steaming" along. The locomotive was given the name "Doddington Dragon" at this time and heraldic crests added to the side panels. By 1980 the park was suffering losses and was closed, the locomotive, her sister, carriages and all trackwork were put up for sale.
When restoration of the Groudle Glen Railway began in 1982 the locomotive (and her sister) were purchased from the park together with all the rails, sleepers and associated pointwork, arriving on the Isle of Man shortly thereafter. In line with previous naming policy (the original locomotives had been named Sea Lion and Polar Bear as these animals were features of the zoo in the glen) the volunteers of the Isle of Man Steam Railway Supporters' Association named the locomotive Walrus and allocated it the fleet number "2". This was the first time fleet numbers had been given to locomotives on the railway, and it was the first engine on site at the railway. Both locomotives were given a green livery and wooden nameplates, and until the return of Sea Lion in 1987, provided all the motive power for the line's public operations and permanent way trains. The locomotive is retained today and performs shunting duties and winter works train duties regularly.
This locomotive is identifiable from her sister as she retains her false dome (actually half a gas cylinder welded to the cladding), and sports dummy side tanks. Other than these visible features she is largely identical to Dolphin in all but livery. Having carried the lighter green livery since arrival in 1983, the locomotive was withdrawn in 1989 and the wheels removed for reprofiling and major engine work. Being surplus to requirements it was several years before this work was carried out and the locomotive lay on blocks in the back of the carriage shed at Lhen Coan for many years. When the line had visiting locomotives in 1998 as part of the Steam 125 event, "Walrus" needed to be stored in the open to accommodate the visitors so the wheels were replaced at this time, and a coat of battleship grey paint applied to smarten her up. War Department transfers were also applied to the false tanks at this time. By 2003 interest had resurfaced (the 50th anniversary of the two the previous year having sparked interest), and over the winter the locomotive was overhauled and repainted into a maroon colour scheme with yellow features. It now operates on gala days and performs works train duties, shared with No.1 "Dolphin". Since returning to service she has been selected for standby duties on Santa Train days, and is renamed annually as "Blitzen" for the occasion. In 2012 to mark the locomotives' 60th anniversary, along with her sister, she received new brass nameplates to replace the 1980s wooden nameplates which have subsequently been mounted for display in the Sea Lion Rocks Visitor Centre and the Lhen Coan Engine Shed.