<Tr> <Th_colspan="2"> Information </Th> </Tr> <Tr> <Th> Gender </Th> <Td> Male </Td> </Tr> <P> Thomas the Tank Engine is a fictional steam locomotive in The Railway Series books by the Reverend Wilbert Awdry and his son, Christopher . He became the most popular character in the series, and is the title character in the accompanying television spin - off series Thomas & Friends . </P> <P> Thomas is a steam engine and has a number 1 painted on his side . All of the locomotives in The Railway Series were based on prototypical engines; Thomas has origins in the E2 Class designed by Lawson Billinton in 1913 . Thomas first appeared in 1946 in the second book in the series, Thomas the Tank Engine, and was the focus of the four short stories contained within . Thomas's best friends are Percy and Toby . </P>

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