How Lady Victoria has got the Holly effect for 50-somethings - after the clothes she wears for her first week in Downing Street sell out

A week is a long time in politics and an even longer time (you'd imagine) if you're the wife of the new Prime Minister, who, as of last Friday, has had to take her place on the world stage looking appropriately dressed for every thing from a day at the races to formal dinners in Washington DC.

Yet, even exiting the plane on Tuesday, ahead of the Nato summit, Victoria, Lady Starmer (or Lady Vic, as she's known in political circles), looked born to this job: glowing and upbeat in a £450 cream, lace-knit dress from British label Needle & Thread, which might as well have had 'breath of fresh air' stamped all over it.

A wife who dresses well is not a requirement of the job of PM, nor should it be, but we all know a natural clothes horse when we see one — someone who understands how to make fashion work for her character and lifestyle and who is confident enough to have some fun with it. 

That Victoria happens to have grace and a chin-up, eyes-sparkling naturalness that you couldn't have dreamed up in a Labour focus group, is definitely something for the new government to smile about.

Just eight days ago, Victoria was a private, working mother-of-two whom we had barely seen in public, so it's all the more impressive that she has hit the ground running. 

It would be tough for anyone to meet all the sartorial expectations of her new role: to stand out from the crowd without stealing the show; to look polished without looking intimidating or frivolous; and at the same time to not lose your own sense of style.

From the little we know of Victoria — a lawyer turned occupational therapist — she would never have chosen this role, but her first week as the PM's wife has been pitch perfect.

On election night, she wore a £295 cropped cream jacket by the British label Me+Em (now almost sold out) with smart wide-leg dark trousers and white flatform trainers. 

This was a soft introduction to the style course she's stuck to since: simple, smart, comfortable. 

Nothing to scare the horses, but very much her own and — that important word given her new position — relatable. 

She looked like she'd happily run with a ballot box or two herself if it'd help.

This was Victoria's last outing as a civilian. 

The next day it was official — the Starmers were heading to No 10 and for that she wore an elegant £275 midi dress in bold Labour red with draped short sleeves, again by Me+Em — a knock-out on her.

A lot of women thought so too, as the brand saw a 300 per cent uplift in traffic and what will be known as that No 10 dress is sold out in every colour bar black.

The Russell & Bromley silver slingbacks, now on sale for £145, were key, too. Other PMs' wives have opted for high-heeled suede courts for such momentous occasions, but Victoria's choice was more youthful and on the fashion money.

You could almost imagine her trying on a pair of 4.5-inch heels, then rejecting them on the grounds she didn't want to be seen teetering when she entered No. 10. 

Also: vertiginous heels somehow separate the wearer from the normal civilian population. Not Victoria's style.

On Saturday, she was pictured at the races at Sandown Park, this time in a green Me+Em print dress. 

It was the perfect occasion for a bright, grassy daytime print — pretty without being fussy. 

She also wore an old pair of Gucci sunglasses — maybe they were borrowed, maybe she has a stylist or adviser of sorts in the wings — either way, they added the finishing flourish. 

For all her naturalness, Lady Starmer isn't averse to a bit of glamour.

On the question of a stylist, a spokesman for Me+Em, her favourite label of the week, founded by British entrepreneur Clare Hornby, confirmed it hadn't loaned the clothes to Victoria, which suggests she is buying them herself without the help of a third party.

But would a stylist change a thing? Not so far, and furthermore she's scoring tens across the board while wearing High Street brands, albeit at the pricier end of the scale.

On Monday, for a low-key visit to Downing Sreet, Victoria was pictured in a Me+Em denim shirt with a ruffle trim (£105) — yes, you guessed it, none left unless you're a size 6 — and flared trousers. 

Nothing remarkable here, but her 'everyday unremarkable' style is the way 50-something women aspire to look. Lady Starmer may just have the Holly Willoughby factor for her generation.

There was a hint of what we might have in store at the Labour party conference two years ago, when Keir Starmer appeared with a lovely looking woman on his arm (could that be his wife?) who was wearing a dark red belted dress and looking, it was noted, more stylish and confident than anyone else in the room. 

The dress was loaned for the occasion by Edeline Lee, a British designer who also loaned her a long 'Weimar' coat, cream top and trousers for a Press night performance of Dear England at the National Theatre.

She's worn Needle & Thread before, too — a £725 romantic lattice embroidered cream gown for the state dinner for Emperor Naruhito at the end of June. We weren't really paying attention then, but we are now.

And so to that other cream Needle & Thread dress, the highlight of the week so far. An 'I'm not afraid to steer my own course' choice, if ever there was one. 

Cream is not the easiest, for all the obvious practical reasons, but it's a smart call for a fresh-faced woman stepping off a plane for her husband's first official engagement.

The £269 gold, woven leather sandals from LK Bennett were spot on, too — summery, dressy and light. 

Suddenly Victoria looks younger than some previous PMs wives and less hidebound by convention, which may be part of the plan. 

Or maybe, more likely, she hasn't over thought it.

For the Nato summit dinner on Wednesday, she chose strong red again, this time a £320 pleated dress with a deep V by French brand The Kooples, a High Street label she's worn before. 

Making her appearance on the balcony alongside Sir Keir and other European leaders, her arm around his shoulder, his hand clasping hers she looked like she was just getting into her stride.

We're looking forward to it.