During the restoration Charles II introduced the waistcoat as a required piece of formal wear for courtiers. It was apparently based upon the clothing worn by the Persian visitors to court and the King thought that wearing this garment would set the fashion of the English and make it contrast with that of the French. At this time it was known as a vest. The term waistcoat is derived from the cut of the garment, being cut at waist level as opposed to the longer dress coat. It is said that another monarch, Edward VII started the fashion to leave the bottom button of the waistcoat undone to accommodate is expanding form.
Waistcoats were required business dress during the Edwardian time and often men kept their pocket watch in the pocket of their waistcoat, a chain fastening it to one of the button holes.
During the 1980s the waistcoat fell out of fashion for everyday business wear and became something which was worn mainly with very formal dress, for example with a wedding outfit or a morning suit.
Recently the waistcoat has begun to make a bit of a comeback. Many more cheaper range everyday suits are sold as three piece and the wearing of a casual waistcoat with a shirt and jeans is becoming a more common sight in the clubs and pubs of England.
I love a waistcoat. Let's wear them.