A definitive sartorial guide to the big day, whether you’re the groom, best man or a guest .

For the past year, we have been running a weekly advice column in The Daily called You Asked, in which we answer readers’ style questions. The most frequently recurring topic is wedding attire. Working out what to wear seems to be a riddle wrapped in a mystery inside an enigma more baffling than a Mr Alex Garland movie.

There will be clues on the invite, some clearer than others. It might state something as obvious as “Dress code: black tie”, as increasingly seems to be the case, especially in the US. But the time of year, time of day and especially the location will also give you pointers. A beach wedding in Ibiza and a country church wedding in England are worlds apart. Even the wedding stationery and wording provide some helpful hints. A formally addressed invitation on stiff embossed card from the bride’s parents suggests it will be a posh do; a Paperless Post email, less so.

But why guess? Don’t be afraid to ask the happy couple to spell out the dress code. Just don’t leave it until the week of the wedding when they will have more pressing things to deal with, such as top-table politics and seating plans, or the excruciating choreography of the first dance. If you have left it that late, direct such questions to the best man.

With wedding season upon us once again, we have decided to dedicate a Dress Code article to comprehensively cover how to brush up for such occasions, from the most formal to the most relaxed.

If you have Celtic blood, the following advice may be entirely inconsequential because any wedding represents a grand excuse to give the old kilt a twirl. There’s always one at every wedding. But when a frisky aunt tipsily lifts it up to see “if it’s true”, don’t say we didn’t warn you.

The more traditional the occasion, the more traditional your outfit. If in doubt, it’s always better to be slightly over-dressed than under-dressed. Peak lapels look sharp, a double-breasted suit sharper still. And dark colours are a good bet, especially if the event runs into the evening. “As an alternative to the traditional double-breasted suit, which can look a bit stiff, try this unstructured navy corduroy version from P. Johnson,” says our stylist Ms Otter Hatchett, MR PORTER’s Junior Fashion Editor. “It is unlined so, even though it’s corduroy, doesn’t feel too heavy.” The silhouette is flattering with its broad lapels and the way it is shaped to nip in at the waist. The corduroy has been blended with two per cent elastane, which gives it a bit of stretch, so you won’t feel too constrained when throwing shapes on the dancefloor.

If you’re wearing a navy or grey suit with black leather shoes, the trick is to make sure it doesn’t look like you’re off to a business meeting (we’ve achieved this effect by opting for Derbies rather than Oxfords). Accessories are important. A matrimonial union is a joyful occasion, one would hope, so add some colour and pattern. That said, overtly colourful shiny silk ties can look too weddingy. This bottle-green polka-dot tie in matt silk from Drake’s is a smarter choice and co-ordinates harmoniously with the jacket’s buttons.

This is a particularly inky shade of corduroy that will look very striking in the inevitable photographs but can almost look black in some lights, which would be too funereal for a wedding. The blue of the shirt combined with the green of the tie help to bring out the navy in the suit. One note of caution about pastel shirts on warm summer days – they do show up perspiration, so if that is a concern, you may wish to stick to a white shirt.

Unless the invitation specifies otherwise, a rural wedding gives you more sartorial licence than a city one. It’s not quite as formal. If you feel the need, the need for tweed (name that film), go for it. Stop short of it going too costumey – you don’t want to look like Mr Marcus Mumford or any of his sons.

A suit is not necessarily a prerequisite. You could wear tailored separates, a double-breasted blazer with a pair of cords, perhaps. Here, we have chosen an unstructured three-piece suit from Barena, which doesn’t feel at all stiff. “This outfit mixes pattern and textures by pairing the Prince of Wales check with a faint stripe in the shirt,” says Ms Hatchett. “If you need to lose the jacket later on in the evening, then the waistcoat will keep you looking smart.” Those with a keen eye for finer details may note that the open-weave texture of the brown knitted tie from Rubinacci helps to draw out the brown in the suit’s buttons.

You can also take a step down in formality with footwear when out of town. Polished black shoes are the usual choice for a city wedding, but brown shoes or boots are acceptable in the country. Brogues or Chelsea boots are an option, but here we’ve chosen a burnished brown monk strap with brogue detailing from O’Keeffe. The leather goes nicely with the strap of this IWC Schaffhausen Portofino watch and they have a chunky rubber sole that is perfect for walking on grass.

Well-to-do weddings in the UK sometimes call for a morning suit, or tails, which few men own, due to the unfavourable cost-per-wear equation, and so most rent. Not ideal. Black-tie weddings are on the rise. Strictly speaking, a tuxedo is eveningwear, traditionally worn only after 6.00pm, but these days, few people pay much heed to that rule. It is a smart choice for a groom and his groomsmen because it’s a timeless look. In 40 years’ time when your grandchildren are looking at the wedding photograph on your mantelpiece, assuming such things still exist in 2058, you’ll be glad you went classic.

If you’re a guest and the invitation says “black tie optional”, wear it. The subtext is “the people paying for your dinner and drinks would like you to wear a tuxedo but don’t want to look like they’re enforcing it”. The point of black tie is to create uniformity. Resist the temptation to express your personality with a novelty bow tie. To borrow Mr Henry Ford’s one-liner, you can wear any colour you like so long as it’s black. Or midnight blue. However, you could switch out the jacket for a jewel-toned velvet number or, as shown here, a cream tux, which is a lighter option for summer, albeit a risky one when red wine is sloshing around.

“Team a cream tuxedo jacket with a pair of midnight-blue trousers for a fresh, more wedding-appropriate take on the black-tie dress code,” says Ms Hatchett. “The mother-of-pearl cufflinks are discreet against the jacket and shirt and don’t compete with the Jaeger-LeCoultre dress watch. Loafers aren’t traditionally worn with a tuxedo, but they’re an acceptable, lighter option now that we’re coming into spring.”

“But I never wear a suit.” Not all weddings are super-formal affairs. Some couples prefer to keep proceedings low key. Not all male wedding guests are suit wearers. Some guys just feel uncomfortable in tailoring. Let’s be clear: we are not advocating wearing sneakers to a wedding unless you are quite sure this is going to be acceptable. And even then, you’re likely to offend an ageing relative. But there are sneakers and then there are sneakers. Many enthusiasts prize them more highly than dress shoes.

This is not a cop-out. It’s much easier and less imaginative to make do in a bog-standard suit and tie. But this is a statement, an assured look, which can be tricky to pull off. It often feels like a sartorial disconnect to wear a tie with trainers, so here we’ve gone for a collared shirt from Joseph worn buttoned up instead. “The yellow collar adds a bit of detail where the tie would normally be,” says Ms Hatchett. “The unstructured Acne Studios blazer has a relaxed shape. Rather than making it a suit, we’ve paired it with navy wool-twill trousers from Officine Generale. The subtle white side stripe adds a sporty edge and complements the minimalist white leather sneakers.” Casual, but still smart.

The location dictates everything here. If you’re a guest, ask the groom and best man what they’re wearing and take your cues accordingly. If you are the groom, do everyone a favour, including yourself, and keep it light and relaxed. You ought to be able to get away without a tie and wear leather sandals instead of shoes, for example. If sandals are a step too far, loafers are a failsafe smart-casual option and can easily be slipped off. Flip-flops, it goes without saying, are a no-no, unless provided by the wedding couple.

Do still make an effort and wear a suit – this is a special occasion – but your tailoring should reflect your surroundings. Go for looser trousers and an unlined jacket to allow air to circulate. And it should be light in more ways than one. Dark colors absorb sunlight, baking you, whereas lighter colours bounce it back. All white everything is for boy bands only, though. You’ll also want breathable fabrics such as cotton, seersucker, perhaps linen. But exercise caution before wearing a linen suit. It can crease badly, so you may want to give it a test run in advance.

“This unstructured Dries Van Noten suit is made from 100 per cent cotton twill and is unlined, so it will keep you cool on the beach,” says Ms Hatchett. The patch pockets will come in handy for your sunglasses. “If you need to take the jacket off, the floral grandad-collar shirt – also by Dries Van Noten – will look great untucked with the cuffs rolled slightly. The colour co-ordinates well with the suit and sandals and the busy print will detract from any perspiration marks.”