Postilion

Postilions at the funeral of President Reagan, 2004
Postilions control the horses drawing the Queen's Coach at the State Opening of Parliament, London 2015
ANZAC horses and postilions struggle to move a gun, Passchendaele, 1917, by Harold Septimus Power

A postilion or postillion is a person who guides a horse-drawn coach or post chaise while mounted on the horse or one of a pair of horses.[1] By contrast, a coachman controls the horses from the vehicle itself.

Originally the English name for a guide or forerunner for the post (mail) or a messenger, it became transferred to the actual mail carrier or messenger and also to a person who rides a (hired) post horse. The same persons made themselves available as a less expensive alternative to hiring a coachman, particularly for light, fast vehicles.

Postilions draw ceremonial vehicles on occasions of national importance such as state funerals.

On the battlefield or on ceremonial occasions postilions have control that a coachman cannot exert.