Far from being something that finished at the waist like the modern waistcoat, this vest was a well-fitted knee-length garment made mostly from cheaper fabrics as opposed to the lace preferred in more lavish times (although it wasn’t that long before this sartorial sobriety was forgotten). As time passed, the vest’s length gradually diminished so that by around 1700, many of the examples of the time had skirts that finished above the knee, a change catalysed for the most part by the demands of being on horseback. As the waistcoat evolved, the front became increasingly more cutaway in order to reveal the wearer's breeches.
As to the question of which came first - the double or single-breasted waistcoat - I’m not entirely sure, but what is more certain is the breakout popularity of the double-breasted style, at least during the early period of the 18th century. By this stage, the waistcoat had developed small flap pockets, had removed the sleeves, and was cut square to the waist. As the sobriety of earlier decades receded, it became common for waistcoats to use patterned fabrics - mostly stripes - but by the turn of the century, the waistcoat had fully arrived in all its splendour, with conspicuous extravagance back in the form of decorative embroidery and luxury fabrics. Dandies were so enamoured with the opportunity to peacock their wares that they even took to wearing more than one at once.
The 20th century was an entirely different story for the waistcoat however as extravagance made way for mundanity once again, before virtual extinction in common everyday dress. The three-piece suit did its best to keep the tradition going, and various subcultures such as the hippies, Teddy boys and punks put their own unique twist on the garment. Despite their best efforts, the casualisation of menswear has meant that the waistcoat as we know it today finds itself best amalgamated in the traditions of formalwear and eveningwear, where it has always felt most at home.
How to choose the perfect waistcoat
So that’s the history - here’s the nuts and bolts of choosing one for whatever occasion you might need it for. The first thing to consider is the style - single or double-breasted. The latter is typically considered the more formal option of the two and comes with a squared-off finish at the waist as opposed to the single-breasted versions angular front. The DB will in almost all instances come with a shawl lapel which accentuates the lovely sweep of the cut and is ideal if you have broad shoulders and are of a medium build. The single-breasted style will be better suited to slimmer chaps.
