Dressing for a wedding? Read the vibe – the rules have changed | Jess Cartner-Morely on fashion

A whole bunch of the traditional rules about what a wedding guest should or should not wear are now obsolete. Take hats. Time was when hats were such a nailed-on part of weddings that “buying a hat” was another way of saying you were invited to one. These days, while a wedding gives you licence to wear a hat if the fancy takes you, unless the ceremony is taking place in a cathedral, it certainly doesn’t raise eyebrows to go without – if anything, a hat wearer will look like a daring outlier.

Other rules have loosened, too. To turn up in white would once have been considered not much short of a declaration of war on the bride; now, an all-white dress code is sometimes requested by the happy couple. To wear black would have seemed a strange and pointed choice a decade or two ago, but the rise of the evening wedding, and the influence of the US, where “black tie” is a standard wedding dress code, has blurred this edict also.

A great wedding outfit is one that looks good on the dancefloor with a toddler on your hip, not one that looks good in a selfie

There’s more. It has always been an unspoken rule of sisterhood that it doesn’t do to look too sexy at someone else’s wedding. The bride is queen for the day, and to draw attention that is rightfully hers is effectively treason. Adult bridesmaids are dressed in shades of lavender that suit absolutely no one to neutralise their beauty, and other women present are to follow their example. But this has shifted too. The modern bride, who may well have a professional hair and makeup team and a suite of two or three spectacular outfits with which to wow the room, is frankly not all that worried that cousin wotsit is going to upstage her with a bit of cleavage. If anything, a bride is more likely to be disappointed if you spoil her photos by looking dowdy. Racy is now better than not making an effort.

In place of the old rules, there are new rules. But I can’t tell you what those are, because the old rules were about obedience to societal norms, whereas the new rules are about obedience to the whims of a specific couple. A dress code, or a moodboard setting the aesthetic which guests are expected to adhere to, is pretty normal now. Even if you aren’t given explicit instructions, it is polite to make an effort to deduce what the vibe is. Is the invite a felt-tip drawing by the couple’s toddler son? Elegant calligraphy on expensively hefty stationery? A reproduction of a 1990s rave flyer? Read the room before you walk into it. The 3pm country wedding – church bells pealing, heels sinking into grass – still exists, but the dress code that went with it is no longer a universal standard. So forget the one-size-fits-all rules, and pay attention to the clues you are given about the wedding you are attending, so that you can play your part in it.

The rules might be laid down by the bride and groom these days, but still I have some tips that are as applicable now as they have ever been. Starting with: for a wedding in the UK that has any kind of daytime or alfresco element, it is better to think in terms of an outfit, not a dress. Much of the mingling happens in the liminal zones between ceremony and dinner or travelling between venues, and often the guest who everyone admires is not the one with the snazziest cocktail dress on the dancefloor, it’s the one shoulder-robing a zebra-print coat over a floral dress for the alfresco aperitifs. Also: if in doubt, overdress. The couple and their families may have been planning and saving for this day for years, so the only true faux pas is not to respect that.

But be kind to yourself, too. They invited you because they love you, remember. So dress to rejoice: wear a dress you can eat in and shoes you can dance in. This is a day to feast and celebrate, not to sit nursing blisters. A great wedding outfit is one that looks good when you are on the dancefloor with a toddler on your hip, not one that looks good in a mirror selfie. So be yourself. Just a scrubbed-up version thereof. That’s all you really need to know. All other rules are old hat.

Styling assistants: Sam Deaman and Nyima Jobe. Model: Kitty Su at Milk. Hair and makeup: Sophie Higginson using Living Proof and Westman Atelier. Dress, £119, Arket. Sandals, £26, ASOS. Sunglasses, £125, Bonnie Clyde. Bag, £99, LK Bennett. Ring, £290, YSSO