This stuff was part of my childhood. My two older sisters had tricycles called James (he was red) Gordon (yes, big and blue) and my brother had another trike called Henry (easy one: green). That was the first time the books came around, and there was precious little commercialism then.
Thomas the Tank Engine is one of the main characters in the series of railway books first written by the Rev. Wilbert Awdry and initially illustrated by C Reginald Dalby (That C stands for the hated name, Clarence). Then gradually taken over by the forces of commercialism and turned into a global brand by first Awdry's son Christopher, for whom the books were first written and finally by Britt Allcroft, who owns all the rights, and exploits them without mercy, in many cases against the wishes of the Awdry family.
The 26 books by the original author are full of references to real railway jargon and practices, and rely on small amounts of exaggeration to tell the stories. As Christopher Awdry began adding to the series in 1983, they became more and more fantastical, until the Allcroft empire stepped in, when Thomas became the star and he and all the others became cutesy characters almost indistinguishable from any other childrens' anthropomorph.
Here's the background to the fictional books. There's this island called Sodor, which is positioned in the Irish Sea, off the English mainland adjacent to Barrow-in-Furness. A bridge links Sodor and the (fictional) town of Vicarstown (Geddit) with the mainland near the (real) town of Barrow. Sodor is about 100 miles in size, and just fits neatly in the gap left between the mainland and the (real) Isle of Man.
Awdry said he chose the name Sodor, and the location because of the strange title of the Bishopric associated with the Isle of Man. It is the Diocese of Sodor and Man. Awdry could find no other reference to Sodor, so he chose to use the name for his fictional island, and place it near the Isle of Man.
The engines live in a shed in the town of Tidmouth on the western side of the island. The whole island is worked out with railway lines and hills and curves and tracks, tunnels and bridges so that the stories are consistent with each other. This is part of their charm.
In the early books (see below), Awdry introduced the six main characters. The first book contains three short stories about Edward, Gordon and Henry. Edward is a willing, cheery worker. Gordon is rather proud of the fact that he pulls the express, and Henry was also a bit too proud of his new green paint.
Only with the second book does Awdry introduce Thomas, though at this point, Thomas is only a lowly shunting engine, not trusted with passenger cars, and left to deal with trucks.
The third book deals with James, and only by the fourth book do we find Thomas on his branch line with his two little carriages, Annie and Clarabel.
More books follow, each describing more and more detail on the island of Sodor, and other railways around the UK until the 26th book, Tramway Engines, when Awdry senior decided to retire.
The original 26 books, together with year of publication.
The Three Railway Engines (1945)
Thomas the Tank Engine (1946)
James the Red Engine (1948)
Tank Engine Thomas Again (1949)
Troublesome Engines (1950)
Henry the Green Engine (1951)
Toby the Tram Engine (1952)
Gordon the Blue Engine (1953)
Edward the Blue Engine (1954)
Four Little Engines (1955)
Percy the Small Engine (1956)
The Eight Famous Engines (1957)
Duck and the Diesel Engine (1958)
The Little Old Engine (1959)
The Twin Engines (1960)
Branch Line Engines (1961)
Gallant Old Engines (1962)
Stepney the 'Bluebell' Engine (1963)
Mountain Engines (1964)
Very Old Engines (1965)
Main Line Engines (1966)
Small Railway Engines (1967)
Enterprising Engines (1968)
Oliver the Western Engine (1969)
Duke the Lost Engine (1970)
Tramway Engines (1972)
This piece written, formatted and edited in Dann's E2 offline scratchpad