Why you should NEVER wear bright colours, silk dresses or feathered hats to a wedding, by celebrity wedding planner JOHNNY ROXBURGH who reveals the secrets to a perfect guest outfit

The invitations are lining the mantlepiece, the presents are bought, the hotels are booked. Now, you just need to decide what to wear to this summer's tally of weddings.

Who better to advise you of the many fashion pitfalls to avoid than society wedding planner Johnny Roxburgh, who has organised nuptials for the rich and famous and personally attended hundreds of them. 

Here, he explains the colours to avoid, the best size for your hat and handbag — and a trick that will make any dress more flattering.

How big is your bag? 

I would recommend you avoid carrying an oversized handbag that looks like you're about to do your weekly shop in Peter Jones.

You don't want a giant tote sitting between your legs all day. I manage to get by with just a pocket in my trousers.

What you want is a bag that is discreet and pretty — a bag that can sit on the table during dinner, like part of the decor, or hang over your chair and look stylish.

Johnny Roxburgh recommends avoiding carrying an oversized handbag. Bag: £450, aspinaloflondon.com 

Carrying a bag that is discreet and pretty is a better option for a wedding. Bag: £69, phase-eight.com

A bag that can sit on the table during dinner, like part of the decor, or hang over your chair adds a touch of style. Bag: £110, lkbennett.com

Linen is out, chiffon is in 

Be very careful with linen. You really need to think about how you are getting to the wedding and how long you will be seated in a car. Too long and the back of you will look like you just crawled out of bed. It's no coincidence that you never see the royal family wearing a fabric that crushes.

If you have bought something particularly floaty in, say chiffon, which won't crease, then take it to a great tailor and have it weighted. They can sew tiny weights into the hem of the skirt so it will hang in a more flattering way — and reduce the risk of it lifting in the wind to reveal your knickers.

You also need to consider the social impact of your sleeves. Draped sleeves look elegant but are a nightmare when it comes to the wedding breakfast or if the dishes are designed for sharing. You'll be dragging all the excess fabric through your (and everyone else's) food. Don't let fashion overtake practicalities.

You could take a chiffon dress to the tailor and have it weighted. They can sew tiny weights into the hem of the skirt so it will hang in a more flattering way. Dress: £475, rixolondon.com

Be very careful with linen. A long distance journey in the car could crease the fabric and make you look like you just rolled out of bed. Dress: £95, stories.com

The perfect hat height 

Avoid wearing a hat that may obscure other guests' view of the bride during the ceremony. I would also avoid a huge plume of feathers. It's not ideal going to kiss a fellow guest and getting an ostrich feather up your nose.

Choose a style with that's no wider than 18 inches and no higher than eight inches. Ideally, it should also be one that can be worn angled so others can access you easily for a kiss.

If you do wear a taller hat, you may have to accept that you sit at the back of the ceremony or no one else will be able to see.

You can't wear a tiara if you're a guest at an afternoon wedding … unless you are actual royalty or the event is white tie and in the evening.

Opt for a jewelled headband or something smaller that has a birdcage veil — something you don't wear every day but won't overpower the rest of your look or irritate fellow guests.

Katy Perry attends the Coronation wearing Stephen Jones millinery and bespoke Vivienne Westwood 

Raffia headband: £49, phase-eight.com

Pink headband: £24, oliverbonas.com

Heels v flats 

Guests should always look at the wedding venue online before they risk wrecking a £1,200 pair of Louboutins on a long gravel driveway. More than anything, shoes must fit properly; no gaping leather at the sides.

Cheap shoes will always gape when you walk in them. Expensive shoes, that fit well, don't.

Go as high as you want with the heels, but you need to be able to walk in them. And if the reception is on a lawn and you're in a stiletto, you will of course sink. I'd far rather see pretty embellished flats that still look special and show you've made an effort.

Go as high as you want with heels but you need to be able to walk in them. Sandal heels: £120, stevemadden.co.uk

Pink court shoe: £139, lkbennett.co.uk

Pretty embellished flats can still look special and show you've made an effort. Flats: £35.99, zara.com

Flats: £85, dunelondon.co.uk

Your colour code 

It's best to avoid strong colours like fuchsia pink or bright turquoise at a wedding, or you'll be unmissable in every single photograph, and no one will thank you for it. It's a very fine line between looking glamorous and smart and trying to steal the show.

It's the bride's day and you should never, ever try to upstage her. It remains the ultimate cardinal sin. For the same reason, go easy on the sparkle. You want subtle embellishment at the cuffs or neckline. 

Top to toe sequins look like you are searching out the photographer's lens and can be noisy when you walk. Heads should turn for the bride, not you rustling up the aisle.

Stick to a palette that works well with your surroundings. If the reception is being held in beautiful grounds and gardens, try florals but avoid anything overpowering. Subtle and elegant is always preferable to attention grabbing.

If the reception is being held in beautiful grounds and gardens, try florals but avoid anything overpowering. Dress: £499, lkbennett.com

It's best to avoid strong colours like fuchsia pink or bright turquoise at a wedding, or you'll be unmissable in every single photograph, and no one will thank you for it. Dress: £189, hobbs.com

Banish beachwear

No romper or playsuits, and definitely no shorts, no matter how tailored they are. Save them for the beach.

And if you're someone who gets very hot, my advice is to avoid silk. Any moisture on it tends to spread, and it will be very hard to hide.

Opt, instead, for a well-cut jumpsuit. Choose one in a special fabric — a brocade or jewel-coloured velvet, no pinstripes. Or palazzo pants are a chic alternative that will look every bit as appropriate in a ballroom, on a country house balcony or sipping champagne in stately gardens.

Opt for a well-cut jumpsuit. Choose one in a special fabric — a brocade or jewel-coloured velvet, no pinstripes. Jumpsuit: £145, phase-eight.com

Don't wear shorts - no matter how tailored they are. Pink shorts: £125, tedbaker.com