William Mitcheson Timlin (April 1892 Ashington Northumberland - 1943 Kimberley), was born in England. He showed remarkable talent for drawing at Morpeth Grammar School, winning a scholarship to the Armstrong College of Art in Newcastle. In 1912 he interrupted his studies to join his parents in South Africa, completing his training in art and architecture and remaining for the rest of his life.

Timlin designed a number of important buildings in Kimberley while pursuing his interest in art, turning out a large number of watercolour fantasies in addition to oils, pastels, etchings and periodical illustrations. His work was regularly exhibited. He also wrote stories and composed music.

Timlin worked on The Ship that Sailed to Mars for two years. It was started as a diversion for his son in 1921. The work expanded until in its final form it had 48 pages of text and 48 colour plates showing remarkable flights of fantasy.

Timlin sent the book to publishers George Harrap, who were delighted with the illustrations and the calligraphic text, deciding to print it without typesetting. The book has since become a fantasy classic. The film rights to the book were purchased in the US, where Timlin enjoyed great popularity. Alan Horne in The Dictionary of 20th Century British Book Illustrators, describes it as a masterpiece and "the most original and beautiful children's book of the 1920s".

The illustrations of this book are on a par with the fantasy illustrations of W. Heath Robinson, Arthur Rackham, Edmund Dulac, Warwick Goble and Kay Nielsen.

Timlin illustrated many South African travel books and prepared illustrations for a book titled The Building of a Fairy City which was never published.