A waistcoat is a formal vest that is traditionally worn with classic suit, tuxedo, or tailcoat. Although vests had been used for thousands of years, the waistcoat is the only men’s clothing item that had been created by Royal proclamation in 1666. King Charles II of England introduced the waistcoat and made it a mandatory clothing item during the restoration of the British monarchy. A diarist wrote: “he King hath yesterday in council declared his resolution of setting a fashion for clothes which he will never alter. It will be a vest, I know not well how.”
Since the 17th century the waistcoat was part of a formal and business attire worn by men. Although quite similar in look and style, the waistcoat worn for formal events is slightly different than the one chosen to wear with a suit. When wearing a suit, the vest traditionally has a higher cut (4 to 6 buttons), is made from the same fabric as the suit, and has an additional buttonhole and small fob pocket used to attach and store a pocket watch. For formal black and white tie events the waistcoat has a much lower cut (2 or 3 buttons), and is also worn in a different color shade than the trousers and the jacket. Traditionally the waistcoat matches the bow tie or the Ascot. For formal events the waist coat is both made in single and double-breasted cut – although the later is much less common.
The correct and traditionally way to wear a waistcoat is without a belt. In fact the waistcoat used to cover up suspenders. In addition some traditionalists insist that the waistcoat worn with a business suit is worn with the lowest button unbuttoned. It is said that this trend was started by King Charles VII (then Prince of Whales), whose expanding waistline required it. Others believe that this trend initially served a more practical reason since leaving the lowest button unbuttoned prevented the waistcoat from sliding up while riding a horse. For black tie events either a waistcoat or a cummerbund should be chosen, but never both
Today waistcoats are much less common for business, and are mostly worn for formal black tie and white tie events as well as weddings. For weddings the waist coat traditionally matches the necktie color.