The Prince Charlie is a very similar cut to the type of mess jackets worn by the military and is probably a "civilianised" version. Officers would wear their full dress uniforms to social events and civilians would want something similar to look as good and impress the ladies - it just didn't have the big epaulettes and silver or gold braid. The double breasted Montrose is also known as a military doublet and no doubt has similar origins. There does not appear to be any equestrian link though. The type of jacket worn by the hunting fraternity (the unspeakable in pursuit of the inedible) was generally bright red (pink they call it) and a longer jacket but without any of the embellishments such as cuff details, epaulettes, silver buttons, tashes etc.