THE ORIGINS OF THE STABLE BELT
The origins come from the Cavalry "Surcingle," a strap either made of leather or webbing, placed over the saddle for extra security in keeping the saddle in place.
While the girth went under the horse in it's normal fashion, the Surcingle went over the saddle, over the girth, to provide extra security. Somewhere during the mid 19th Century Cavalry Troopers noted that taking bits of these surcingles, shortening them, and adding smaller buckles, were very handy at providing lower back support on long marches. In fact I use them for the same purpose riding to hounds or for three day eventing.
As time passed different regiments got them in Regimental Colours, and they gradually became more decorative and tribal. However, to this very day, the two buckled stable belt can't be beaten for its historic purpose - cinching you in and giving support.
With thanks to Stephen.E.Henthorne, FRUSI, MInstF, ACIArb, CWCP
Joint-Interagency-Multinational Stability Operations