The Fat Controller (Sir Topham Hatt) bought Duck from The Other Railway in 1955 to take Percy's place as station pilot at Tidmouth. Since The Fat Controller had been apprenticed at GWR's Swindon Works, he allowed Duck to return to his original Great Western Railway livery, and retain his number '5741', which Duck wears proudly on cast brass numberplates on his cab sides.
Duck is not actually his real name. When he first arrived, he explained that his real name was Montague, but he was usually called Duck because everyone said he waddled. Although he claims this was not true, he prefers Duck to Montague, and now that is what everyone calls him.
Despite an incident when a devious engine called Diesel spread lies about him, the Fat Controller realized what a useful engine he had in Duck, and eventually gave him a branch line of his very own.
Duck's branch line runs between Tidmouth and Arlesburgh and is nicknamed The Little Western, as all the locomotives and coaches have been restored to Great Western Railway livery. Duck shares the passenger duties with Oliver, but has his own two autocoaches: Alice and Mirabel.
Duck sometimes helps on other lines. He makes friends easily, and the Fat Controller says that he makes everything run like clockwork. "There are two ways of doing things," Duck says, "the Great Western Way or the wrong way." This has been known to annoy the other engines.
The nickname "Duck" comes from Rev. W. V. Awdry's OO scale model railway. He had bought a GWR Pannier tank engine manufactured by Gaiety as a spare engine for his model railway, but one of the wheels was not quite concentric, and the model had a pronounced waddle, earning the nickname "Duck" which stuck long after new wheels had been fitted.
Duck is based on the 57xx class built by the Great Western Railway and still carries the colours of the GWR. These engines were designed to shunt and to work branch lines, and many were still working beyond the end of steam on British Railways. Several are preserved on steam railways up and down the United Kingdom, where they have proved as useful and versatile as Duck himself.
In the biographical work The Thomas the Tank Engine Man, Rev. W. Awdry recalls seeing pannier tanks at work on the Great Western Railway at Box in Wiltshire, where he lived as a child. These would not have been 57xx tanks, but might have been an early influence nonetheless.
Duck never stands nonsense from other engines. He is 100% serious, but can still be cheeky sometimes.