Black tie, charity dinners and what the invitation means

The dress code is printed in the bottom right corner of the card, in the smallest type on it. Read it before you book anything. "Black tie" and "black tie optional" aren't the same instruction, and "lounge suit" means neither. Get that line wrong and you'll spend the drinks reception being the only man in the room with a long tie on.

Most people don't own a dinner suit. That's fine. The fix takes about ten days if you hire and about three weeks if you buy and need alterations, so the moment the invitation lands, check the date and count backwards.

What the words actually mean

Black tie. A dinner jacket, not a suit jacket. Black or midnight blue, with silk-faced lapels, a matching stripe down the trouser leg, no belt loops. Bow tie, black. Something covering the waistband, either a cummerbund or a low-cut waistcoat. Black shoes, polished hard.

Black tie optional or black tie invited. They'd like dinner jackets and they know some guests won't have one. A very dark charcoal or navy suit with a white shirt and a sober tie is acceptable. You'll be in the minority of a well-dressed room, not the wrong room.

Creative black tie. Dinner jacket, but the host is inviting a velvet one, or a coloured bow tie, or a black shirt if that's your thing. Read the event before you take the invitation too literally. A hospice fundraiser in a county hotel isn't the place to test a burgundy smoking jacket.

Cocktail or lounge suit. A proper suit. Dark, pressed, with a tie unless you know the crowd. No dinner jacket.

White tie. Rare. Tailcoat, white marcella waistcoat, white bow tie. If you get one of these and don't already own the kit, hire it and let the shop dress you.

For women, floor length is the safe read of black tie, but a well-cut midi in a proper evening fabric has been fine at every gala I've attended in the last decade. Fabric does more work than hemline. Crepe, silk, heavy satin, velvet. Jersey that photographs like a beach cover-up doesn't.

The six details that get noticed

Nobody inspects your jacket lining. They do notice these.

• A self-tie bow tie. A pre-tied one sits too flat and too level, and at some point in the evening it'll go crooked in a way that looks careless rather than charming. Learn to tie one. It's the same motion as your shoelaces, done vertically, and it takes about twenty minutes of practice in front of a mirror.
• Lapel and bow tie in proportion. Narrow lapels with a wide butterfly bow looks off. Match the rough width of the bow to the widest point of your lapel.
• The waist covering. A shirt showing between jacket buttons and trouser waistband is the most common black tie mistake. Cummerbund pleats face upwards. Yes, it was originally for catching crumbs. Yes, that's why.
• No belt. Dinner trousers are cut for braces or side adjusters. If your hired pair has loops, the shop has given you a suit and called it a dinner suit.
• Socks over the calf. Black, thin, long enough that no ankle shows when you cross your legs at the table. You'll be seated for two hours.
• Shoes that are actually black. Patent leather is traditional. A plain oxford in smooth calf, polished until it reflects, is fine and more useful the rest of the year. Brogues aren't. Neither is anything with a rubber sole and a visible seam.

Hire or buy

Hiring makes sense for one event, or for a shape you don't want to commit to. Buying makes sense from about the third wear, and a dinner suit dates far slower than a business suit because the design stopped moving decades ago. A decent one bought at thirty is still correct at fifty, assuming your waist is.

The trap with hire is the fit. You'll be handed a jacket cut for somebody else's shoulders and told it's your size. The shoulder seam has to sit on the edge of your shoulder bone. That's the one thing a tailor can't cheaply fix, so refuse the jacket if it's wrong and ask for another. Sleeves and trouser length they can sort in a day.

If you're buying, budget for alterations on top of the price of the suit, and get the trousers hemmed with a slight break or none at all. A puddle of fabric over the shoe ruins the whole line.

One thing worth spending on either way: a proper evening shirt. Marcella or pleated front, turndown collar, double cuffs. A normal business shirt under a dinner jacket looks like you got dressed in a hurry.

A charity dinner is a specific kind of evening

It isn't a wedding. The shape is usually a drinks reception standing for forty-five minutes, a seated dinner at a table of ten with people you mostly don't know, speeches between courses, and an auction or a pledge round that people underestimate.

Plan for the standing. New shoes at a charity gala is a self-inflicted wound. Wear them around the house for a few evenings first, and put a plaster on the back of each heel before you leave if they're stiff.

Bring a card and know your limit before the auction starts. These rooms are engineered to make you generous, which is largely a good thing, and there's nothing wrong with deciding in the car what you're willing to give. Say it out loud to your wife and stick to it. Tell the table you're the cheap one and enjoy the evening.

Women: check whether the venue has a cloakroom, and whether your dress has anywhere to put a phone. It won't. A small clutch that fits a phone, a card and a lipstick is the whole kit. Heel height is a real decision if there's a receiving line and a long walk across a car park in November.

The bit people skip

You will be seated for three hours next to somebody you've never met. That's the actual event. The clothes get you through the first ninety seconds.

Ask the person on your left what brought them to this particular charity and you'll get a real answer more often than not, because almost everyone in that room has a reason. Somebody's brother. Somebody's daughter's ward. The organisers put a table plan together for a reason, so don't spend the night talking across the table to the one person you already knew.

Two other small things. Arrive at the stated time, not fashionably late, because the reception is when the organisers actually get to speak to people and the doors to the dining room close on a schedule. And find whoever ran the evening before you leave and thank them by name. They've been on their feet since two in the afternoon.

The suit is a courtesy. You wear it because somebody spent months getting a room full of people together for something that matters, and turning up properly dressed is the cheapest contribution you can make. The expensive one comes later, when the paddle goes up.