Arthur took great pride in his spotless record, which he soon lost after colliding with Duck's trucks in an incident largely provoked by Thomas. However, this spotless record was soon amended, after Thomas apologized to him for causing the accident.
He was bought to shunt and pull goods, but then was transferred to the coastal run, on which he enjoys working. He is responsible for this line, which is famous for its fish. Arthur is the only known engine (with the exception of Salty and Porter) to enjoy the smell of fish.
Arthur is a big tank engine who has never been naughty in his life. He was highly esteemed for his "spotless record" before he arrived on Sodor, never having made a mess or a fuss and never having caused an accident. His main duties were to shunt trucks and haul goods trains. Arthur can be a bit naive however and after a jealous Thomas tricked Arthur into setting his standards too high with the trucks, his record did not stay as spotless as he had hoped. Arthur is very obedient, cautious, and well-behaved. He aims to please in his work and do everything as best he can. He now mainly runs the Fishing Route by the coastal village, a duty which Thomas was only all too grateful to be relieved from. Here, Arthur enjoys the sea air and the smell of the fish.
Arthur is an LMS Ivatt Class 2MT tank engine developed for the London Midland and Scottish Railway (hence the initials on his tanks).
Arthur is painted LMS maroon with gold boiler bands and yellow lining and "LMS" written on his side in yellow. His livery is inauthentic: if Arthur had been one of the ten 2MT tanks built for the LMS, he would have been painted postwar black with "LMS" written on his tanks.