YEOMEN OF THE GUARD.
In very welcome contrast to the sober grey of the Tower of London is the bright red uniform of its warders-the Yeomen of the Guard, These men are commonly called Beefeaters, a title as to the derivation of which etymologists differ. Some explain it as a corruption of "buffetiers," or waiters at the royal buffet; others trace it to the rations of beef formerly served out to the men while on duty. Be this as it may, the Yeomen of the Guard are veterans who have all more or less distinguished themselves on the field of battle. On State occasions they sometimes constitute a picturesque guard of honour; and at the opening of each new Session of Parliament a body of them searches the cellars of the Houses of Parliament as a precaution against any "gunpowder treason and plot."
source: The Queen's London : a Pictorial and Descriptive Record of the Streets, Buildings, Parks and Scenery of the Great Metropolis, 1896