Samantha and David Cameron outside No.10 after this year's election victory / Rex Features
If Samantha Cameron is top of the annual best-dressed list in 'Vanity Fair', vying with minor royals for the honour, what does this say about the criteria? Alexander Fury is baffled

Is Samantha Cameron the best-dressed woman in the world? Of course not, you scoff contemptuously. Don't be preposterous. Besides, best dressed for what, exactly? And should we be focussing on how someone looks rather than what they do, either to their detriment or falsely to their credit? It's problematic.

Vanity Fair magazine, however, has placed Cameron top of its list of best-dressed women for 2015. And it's a problematic list, at least for me: it contains women such as HRH the Countess of Wessex, HM Queen Letizia of Spain, and Charlotte Casiraghi. (She doesn't have a title – because her mother, Caroline Princess of Hanover, refused them at her birth. She is, however, eighth in line to the Monégasque throne.) SamCam herself is daughter of Sir Reginald Adrian Berkeley Sheffield, 8th Baronet, not just the wife of the Prime Minister of the United Kingdom.

Samantha and David Cameron arrive at a polling station to cast their vote on 6th May (Getty)

All that minor European royalty – none of it especially ostensibly fashionable, bar Casiraghi, who fronts Gucci's make-up line – give the list a stilted, stagnant air, of pomp and privilege. It feels like it could have been created in about 1955, give or take Grace Kelly and the Duchess of Windsor. Haven't we moved on – in terms of fashion, and our view of women as being more significant than ornament?

I'm not saying Vanity Fair is rampantly anti-feminist: indeed, it's an equal opportunities offender. There's a men's "Best Dressed" list too, populated with more royals (Prince Harry, Carl Philip of Sweden) in unexceptional clothing. There are also a Hollywood and fashion industry lists that intermingles the sexes. Azzedine Alaia, the French designer who only wears black cotton Mao-style pyjamas, tops one of them, dedicated to "Originals". Which is quite great.

Samantha Cameron next to Vogue editor Alexandra Shulman at London Fashion Week (Getty)

But back to SamCam, and her supposedly world-recognised style. Now, I don't want to rip Cameron to pieces. She doesn't deserve that – at least, not stylistically. But nor does she deserve a best-dressed accolade. Cameron's clothes are perfectly adequate, in a sort of mumsy, toff-y, Chipping Norton way.

She used to be creative director for Smythson, and continues to consult for the label's expensive leather goods. She wears lots of British designers, acting as an ambassador for British fashion by sporting labels such as Vivienne Westwood, Christopher Kane and Michael van der Ham (not British, but he lives and shows here). She turns up at their shows to smile and nod and not express an opinion. Sometimes she invites them round to 10 Downing Street by way of a slap on their collective, stylish backs – albeit avoiding questions about her husband's education policies, which threaten the creative industry as a whole.

Cameron dresses fine, for what she has to do. But she's no Michelle Obama, whose dress sense has, in a narrow way, revolutionised the role of the First Lady in promoting American fashion. (Where is Obama, by the way?) Maybe she's been ubiquitous – but she's more conspicuous by her absence.

The Camerons attend a service at Westminster Abbey on 10th May (Getty)

Lists like Vanity Fair's annual best-dressed are odd, regardless of who they champion, because you're left wondering by what criteria they rank their honoured few? Why does SamCam's "Conservative charm" nudge her above the number two, Taylor Swift, for instance? She leap-frogged Rihanna, whom I would have personally pegged for the top spot – because she's bold, and seems unafraid yet not unhinged, a pitfall that has floored a number of her contemporaries (there isn't a whiff of Lady Gaga anywhere near this year's list, FYI).

Rihanna and SamCam. That's an odd mix, in a sentence. But really, the dress of each isn't so different. Rihanna wears clothes engineered for her performances; so does Cameron. Cameron's are possibly easier to digest than the cloak by Chinese designer Gui Pei that Rihanna sported for May's Met Ball, quickly Photoshopped into a million online memes to resemble omelettes or Cornish pasties. Cameron would never take that risk. Perhaps it's SamCam's middle-of-the-road consistency that Vanity Fair is lauding? That, in 2015, she's been highly visible but hasn't put a foot wrong. I suppose that's worth a round of applause. But only a conservative one.