Five rules for sartorial success at Royal Ascot In many ways these amendments are semantic, a light dusting of the old rules. While that's helpful, they can't aid those of us who don't feel right in conventionally formal attire Oh, we had such problems on this shoot. One outfit looked all right but made me feel 150. One made me look like Widow Twankey, and subsequently feel murderous (memo to those under 5ft 8in: avoid huge-brimmed hats unless actively seeking a comedy outfit). One, a trouser suit, felt fine. But did it really look the part? Did I just say part? Therein lies the nub of this whole psychodrama. If, as the canny bard says, all the world's a stage, then going to Royal Ascot or a similar formal occasion is the Cannes Film Festival, an Oscars acceptance speech and auditioning for a self-castration scene in a Lars von Trier movie all in one. If you're not a seasoned pro, it's hardcore role-playing. Fashion hits at Royal Ascot 2011 in pictures By now you're probably thinking: come off it love, you're the fashion editor. Your wardrobe should surely be teeming with appropriate Ascot wildlife - the pheasant-plumed hats, the shiny croc accessories. Well, you'd be wrong. I attend fashion events with a faintly alarming frequency. But they're not the same thing as Ascot, being all about looking stylish and au courant rather than appropriate and smart. Thus I approach this from a similar angle to those who also find themselves required to dress in unfamiliar garb once in a blue moon: ie a place of deepening panic. The good news, in one sense, is that Ascot has tightened up its rules. Fascinators are out. Headpieces with bases in excess of 10cm in diameter are in. Trouser suits are permitted in the Royal Enclosure (they always have been). Strapless dresses, midriffs, halter necks and shoulder straps narrower than 2.5cm have been banished, probably to Aintree, where they are free to roam with crotch-skimming skirts. From now on it's all about the knee-or-just-above length. While that's helpful, they can't aid those of us who don't feel right in conventionally formal attire. Lisa wears: Hat (left) £149 Whiteley at Fenwick and Hat (right), Piers Atkinson at Fenwick, 020 7629 9161. Jacket £100 Oasis; oasis-stores.com. Dress £395, D&G at Harvey Nichols; harveynichols.com. Shoes £185 Lucy Choi; lucychoi london.com But in true existential spirit, we can help ourselves. 1 Don't splurge on something you'll never wear again. You'll resent it and sulk the whole day, blowing your children's inheritance on an unlikely sounding nag, just to sabotage the whole blasted affair. Whatever your particular foible - trousers, khaki, believing yourself to be one of nature's flower children, go with it. Be sure to invest in top-quality versions thereof. Marni and Etro make boho look positively chic. If you decide on a trouser suit, go for a delicious, feminine colour. 2 Scrimpeth not on accessories, especially not on the hat, especially if you're in a trouser suit and don't want to be taken for a seditionary. Piers Atkinson and Gina Foster are two of the best youngish milliners around with hats that are striking without being ludicrous and prices (£300 up) within the boundaries of reason. Even if you never wear your hat again, it will make you feel a zillion dollars and serve as a lovely Kapoor-esque sculpture ever after. Fenwick of Bond Street, which opens a pop-up Atkinson shop this month, is brilliant for occasion wear, from classic MOTB suits and dress-coat duos, to less traditional trouser suits. Royal Ascot fashion: Mad hats 3 This summer's Fifties-style prom dresses (see Jonathan Saunders), worn with a cropped cashmere cardigan, are a playful alternative to the traditional suit - and look gorgeous on curvy figures. 4 Fitted is generally smarter than baggy. If you feel best in a smock, wear a belt. 5 The high and middle street (Malene Birger, MiH and Raoul) have some pretty summer-tweed jackets. If the fit isn't absolutely right, get it altered. It's what the Duchess of Cambridge does with her high street buys and it makes all the difference.