However, the sheer variety can increase wardrobe dilemmas, because it can be difficult to know how to hit the right note and not be either too overdressed or underdressed. It's a danger to think that anything goes.

For the modern marriage, no matter how posh or casual, never has research been more important, so that you don't inadvertently look as if you are trying to outshine the real stars of the Big Day.

First and most important, don't go whiter than the bride and that means don't wear white or cream. Be careful with nudes and beiges, too – if you do go for a buff or a blush, or putty or pale caramel, be sure to team with a strong accent colour, say, on a cami top, if it's a suit, or with accessories (even black), so there is no danger of anyone thinking for a second that you might either be the bride or be attempting to outshine her (it's also a good idea to find out what colour the bride and groom's mothers are wearing, especially if you are of a similar age).

Traditionally, it's considered impolite to wear black, but that's a bit old-fashioned now (the only ones who will tut will be the types who will tut at everything anyway). Black is sleek, stylish and dressy, but again it's a good idea to tone it up with a brighter accent colour, or with a gleaming metallic, so no one can wonder whether or not you are mourning the loss of either the bride or the groom's single status.

Don't wear jeans, ever. Not even if it says "casual" on the invitation, not even if it's just for the evening do, not even if your jeans cost £250. It's disrespectful. Jeans are never smart, no matter how glam the top, although if it's a cowboy-themed wedding, you might get away with it.

Don't ignore the dress code, even if it's fancy dress. You have the play along with the happy couple's expectations and dreams. If they want everyone wearing pink or in Harry Potter inspired costumes, do your best, even if it's just a nod to it.

There are many weddings, such as ones between older couples or couples who have been together for a while and already have children, for which you can feel overdressed, rather than underdressed. In fact, weddings with no dress code, where it's assumed that the bride and groom want a relaxed feel, can pose more wardrobe problems than white tie.

It's especially hard where the bride chooses not to wear white or cream, as you can't help but worry about turning up in exactly the same colour. If you can, try to find out to avoid embarrassment.

Also, approach wearing long with care, as you might find that only the bride and you are doing so (or even just you), which is fine, but you must not look like a bride, so avoid up-dos, flowers in the hair and certainly no tiaras.

This season, long is hard to avoid because the maxi dress is such a big trend and so perfect for weddings. If you do go for a long dress (after all, it is lovely to show joy and respect for your bride and groom by dressing up for them), make sure it's not white or cream or the same colour as the bride's outfit (that's the most important bit), and steer clear of satin or anything shiny or metallic. Then, if still in doubt, dress down your long frock with accessories – a wide brown leather belt is a good idea, as is a jacket (even a gorgeous leather one), plus lots of bangles and necklaces.

A neat but chunky leather bag should certainly do the trick.


Dress code: What does it all mean?


White tie: For men, it means a tail coat, one step up from a dinner jacket (though, apparently, you can just about get away with the traditional dinner suit), with a white bow tie, stiff white shirt and waistcoat. For women, a long dress (that means three-quarter length at the shortest).

Black tie: Tuxedo or dinner suit for men. For women, glamorous and smart – a dress or separates with a dressy or evening feel.

Formal dress: For men, usually means black tie, but can be a smart suit (but check). For women, fairly flexible, from a cocktail dress, smart suit or long dress. It's fine for women to wear trousers to formal events, if they are suitably dressy, but if it's a very formal function you might want to play it safe.

Smart/casual: Shirt and tie, usually, but not always, with a jacket. For women, it can be a dress, skirt or smart pair of trousers, with heels, jewellery and glam top.