The Expedition of Humphry Clinker was the last of the picaresque novels of Tobias Smollett, first published in 1771, and is considered by many to be Smollett's best and funniest work. It is presented in the form of letters written by five different characters. The author's own travels in France and Italy helped provide inspiration for the plot.

Warning: wikipedia contains spoilers

The title character, Humphry Clinker, is an ostler who does not make his first appearance until about a quarter of the way through the story, when he is taken on by Matthew Bramble, a Welshman, and his family who are travelling through England. Various adventures befall them, especially after their meeting with Lieutenant Lismahago, a Scotsman, who joins their party. After various romantic interludes, Humphry suffers false imprisonment but is rescued and returned to his sweetheart, the maid Winifred Jenkins. It is then discovered that Humphry is Mr Bramble's long-lost son.