There’s something about ‘the fashions’ that sends me spiralling into panic.

Even though I’ve been attending shows in New York, London, Milan and Paris for decades – including 12 years gracing the front row as a fashion director for both Glamour and Stylist magazines – the stress over what to wear never goes away.

And this season, keeping my cool among the world’s most style conscious is going to be tougher than ever. That’s because I’ve set myself a cost of living crisis challenge. Instead of dressing in my usual fashion week uniform of Chanel shoes, a hot new top-handled tote and a statement trench coat – at a total cost of several thousand pounds – my fashion jaunt will see me styled head-to-toe in supermarket chic.

Yes, I have pledged to wear nothing at London Fashion Week that you can’t pick up on your weekly shop at Asda, Tesco or Sainsbury’s.

At 45, I have recently removed myself from the intensity of the fashion pack by upping sticks from London to Norfolk. No longer employed full-time by the big fashion hitters, and without the support of a magazine team around me, the pressure of showcasing my most stylish self is immense.

Can I really do it in clothes you can whizz through a self-checkout? I admit I used to revel in parading for the street style photographers who wait to snap fashion week attendees. I’d choose my outfits to ensure I’d catch their eye, including hats, big heels and bold colour, along with whatever the It item of the season was. This wasn’t hard. Not long ago, brands were wildly generous, gifting me four-figure handbags and inviting me into stores to choose pieces.

Sometimes even top tier designers like Dolce and Gabbanna or Givenchy would offer me a loan. It was a treat to wear such expensive clothes, if only for a few hours. Getting your picture taken was validation that yes, you had put together a great look.

At the same time, I have never been averse to a bit of browsing in the supermarket clothing aisles. I vividly remember the excitement of finding a dove grey cashmere cardigan in Tesco in the early Noughties. No one ever guessed where it came from.

Little did I suspect, however, that I’d be searching out outfits for fashion week next to the frozen pizzas and bagged salad. The instructions from my editor are firm. No cheating with designer accessories to elevate my look (a tried-and-trusted stylist’s hack) and no M&S.

Alexandra Fullerton wears supermarket clothes to London Fashion Week, sporting a Tesco trench coat while watching the catwalk

I have never been averse to a bit of browsing in the supermarket clothing aisles, says Alexandra (pictured in a Tu fur coat at a Toga show)

Remarkably, it’s the latter rule that makes this a tough assignment. Ask any fashionable woman what she’s wearing and at least one component of the look is likely to come from Marks. But with M&S’s fashion cred now an open secret, the brand is off the table for this challenge.

On fashion week eve, the nerves kick in. I don’t think I can do this. As I gaze down at the clothes I’ve popped in my trolley alongside the teabags and broccoli, I lose faith in my ability to pull them off.

After all, this year’s London Fashion Week is a big one: Alexander McQueen is showing in London after 25 years in Paris and Christopher Kane is back with a new role at Mulberry. And the buzz around the M&S show is adding yet another layer of excitement.

While I never rely on prohibitively expensive items, during fashion week clothes are my armour. London, more than other fashion capitals, has a reputation for bold ideas on the catwalk which translates into dressing adventurously for the guests. My inclination is to keep it simple, but I know this won’t cut it on the ‘frow’.

Having said that, democratically-priced (and sized) supermarket fashion is having a moment. Last year when Yasmin Le Bon was the face of George at Asda was a turning point. Then fashionistas started whispering about the offering at Tu at Sainsbury’s including the barrel jeans in every shade that only cost £12. Significantly, 81 per cent of shoppers now believe the clothes have improved. I agree with that. So how hard can it be to find three outfits that will cut the mustard with the fashion crowd?

Here’s how I got on…

DAY ONE: Alexandra wears comfortable jeans that cost just £18 from George at Asda, practical trainers and a cashmere jumper from Tu at Sainsbury’s

Alexandra says she felt chic wearing her Tesco trench coat, popping the collar and rolling up the sleeves of the jacket

Day one

I begin my experiment by going for a look I dub ‘the understated editor’. I pick out some comfortable jeans that cost just £18 from George at Asda, practical trainers and a cashmere jumper from Tu at Sainsbury’s. Cashmere at the supermarket? I’m here for it.

I throw Tesco’s trench coat over the top then pop my collar and roll up the sleeves. I look chic. I feel chic. The trench at £55 is surprisingly weighty and also reversible, which halves its cost per wear. I dash to Bora Aksu’s show – a designer who creates extravagant confections of tulle, ribbon and whimsy. I feel drab, compared to other guests wearing the label’s iridescent ball gowns at 11am, but happily I bump into a stylish writer friend who tells me, unprompted, that she loves my coat.

‘You’ll never believe where it’s from!’ I gush. She runs her finger over the buttons and belt and coos in approval. I almost hyperventilate with pride. A strong coat is key at LFW. It’s the first layer most people notice and F+F have created a style that’s on-trend yet timeless. (Unsurprisingly, the Tesco trench is their biggest selling online fashion item, ever.)

I hear my name called out. A PR waves me past a seething queue and ushers me to my seat. To my huge relief I’m in my usual spot – on the front row.

Day two 

I use all my styling skills and cram as many autumn trends as I can into one outfit: ‘the influencer look’. George at Asda’s £38 funnel neck jacket. Tick. George at Asda’s £20 asymmetric-hem skirt in heritage check. Yes. Tu at Sainsbury’s £20 ruched loafers and £38 tan suede bowling bag? Of course!

I’m a walking fashion victim, but it works – and all for £116.

As I head into the venue for the show from designer Patrick McDowell (who dresses The Princess of Wales), I’m called out by a street style photographer, which is just the validation I’m after.

I chat to friends before the show, swishing my George skirt and playing with the jacket’s collar to entice compliments but no one bites. One friend says I look fabulous but years in the business tells me it’s more automatic platitude than genuine outfit appreciation.

Alone, the pieces are terrific, but the overall mix is too trendy and lacks individuality. Every stylist knows the default formula to create interesting looks is to mix high and low.

Normally, I’d pick one supermarket piece, then elevate it with a designer accessory plus something old, to add personality. Today, in a sea of vibrant creativity provided by the guests around McDowell’s catwalk – and the exquisite creations on it – I look mediocre.

I decide it’s better to wear a bin bag than to look boring and can’t wait to change into my final look, although this was the trickiest outfit of all…

DAY TWO: Alexandra wears Asda’s funnel neck jacket, George at Asda’s asymmetric-hem skirt in heritage check, Tu at Sainsbury’s ruched loafers and a tan suede bowling bag

DAY THREE: In fluffy jacket and a sheer black £26 dress, both from Tu

Day three 

I call this one ‘the peacock’. My natural tendency is to underdress, but true peacocks wear cocktail dresses and stilettos before breakfast. At the beautifully minimalist show by Japanese label TOGA, I’m certainly not in the most outrageous outfit but I still feel ridiculous. My fluffy jacket (£45 from Tu) takes up more space than I do and although my sheer black £26 Tu dress echoes the diaphanous fabrics on the runway, it’s synthetic and has creased.

I feel shabby. And sweaty. Did I imagine it or did the person sitting next to me just sneer at my shoes? I added a hat for the studio shoot but can’t bring myself to wear it here. It’s a fabulous piece but too audacious, not to mention hot for this humid afternoon. Outside I tear off the jacket and slip out of my heels, frustrated.

Every woman knows the pain of being dressed in something that isn’t right for the occasion, the weather, or your mood. It’s agony and can ruin the entire day. Magnify that feeling ten-fold for LFW. This is one outfit I won’t be revisiting.

Yet, overall, the experiment has made me realise that a chic supermarket sweep is possible… so long as you don’t try wearing it head-to-toe, to a fashion show, on a milder-than-expected autumn day.

The cachet and comments I received for my check F+F trench makes me think Tesco is hot on the heels of M&S in the fashion stakes, though Tu at Sainsbury’s is also a strong contender. Its stand-out pieces focus on natural fibres – suede, cashmere, lambswool – which adds credibility.

The low prices are also a temptation. Everyone’s budgets are stretched, yet none of us can resist a treat. A supermarket buy is a double win. I’ll definitely be adding more gems to my trolley in future.