Bogart wears a tropical dinner jacket, with shawl collar

A man’s dress used to be driven by social propriety – what his peers considered to be fit and proper. Most of the rules for dress that we have inherited were formalised by social norms. Style icons were made when those that could (usually royalty) broke with convention and wore. Hence the wearing of suede shoes and double-breasted jackets by Edward VIII when he was Prince of Wales. He made that acceptable – but he was not necessarily the first to do so, just the first to sufficiently encourage others to follow his lead.

Today, there is little of this social propriety left. Men in some offices know they have to wear a suit and smart shoes. Some social fixtures, such as race meetings, have dress codes. But that’s about it. The only area today where men know their dress is prescribed is when wearing a dinner jacket, or black tie.

However, common mistakes are still made. The biggest is that a man’s waist is often not covered. With black tie you have three options: waistcoat, cummerbund or double-breasted jacket. All cover the waist and conceal that part of the shirt. They are listed in declining order of formality (unlike most other areas of dress, double-breasted is considered less formal than single) and a man must wear one of them.

This choice then goes some way to determining the shirt a man wears. Most evening shirts have stiff or starched fronts in some shape. A small or oval front is designed to sit under a waistcoat, so only that part of the shirt is exposed when one’s jacket is open. A cummerbund leaves more of the shirt exposed and must therefore be worn with a wider stiff front in a rectangular shape. Being less formal, it may also be worn with a pleated front and turned-down collar. Stiff-fronted shirts most often have a wing collar, though this is not universal.

So the second biggest mistake men make is to mis-match the formality of waist covering, shirt front and collar. Each is on a sliding scale and must not be too far apart from the others.

The third biggest mistake men make is probably wearing black tie during the day, something the Americans are particularly guilty of. Black tie is evening wear. That is why it is black.

Or at least dark. Black tie can in fact be midnight blue, brown or any other dark colour. Midnight blue was popularised again by the Prince of Wales, and often looks darker under lights than black. Noel Coward had a brown outfit, complete with matching tie and pumps, made for him by Douglas Howard. Some rakes of the past have worn dinner jackets in all the colours you commonly see smoking jackets in today. However, I would only recommend the first of these alternatives – midnight blue.

The jacket should have a peaked collar, rather than a notch or step. This reflects the outfit’s antecedents in the morning suit and frock coat. A shawl collar is acceptable but is more casual than peak. It is often found on double-breasted or smoking jackets – or indeed more casual dinner jackets like a tropical-weight ecru, famously worn by Humphrey Bogart in the film Casablanca.