"where they last changed horses, see the postilions"
A Coach With Two Extra Horses, Ridden by a Postilion - 1793
Public DomainA Coach With Two Extra Horses, Ridden by a Postilion - 1793 - Credit: Rowlandson

A postilion rode on one of the horses (usually the left one) pulling a carriage. His job was either to guide the extra horses or to guide the carriage if there was no driver.

Under normal circumstances, a carriage would hire horses to make better speed. It was the postilion's job to go with the horses all the way to the next stop, where he and the horses would be replaced.