This story is from Why do we wear suits? an episode of The Why Factor presented by Mike Williams and produced by Smita Patel. To listen to more episodes of The Why Factor from the BBC World Service, please click here.

Nestled in London’s Mayfair neighbourhood is the shopfront of Henry Poole & Co at the heart of Savile Row – a street synonymous with the crème de la crème of men’s suits.

The firm dates back to 1806. During the century that followed, British fashion became a global phenomenon and its favoured sombre suit an international norm. But why?

Some would say it is functional, I think it’s more a case of: it carries connotations of modernity and functionalism and status - Valerie Steele

Given the price tag of each Henry Poole & Co suit (around $5300), it would be easy to assume bespoke suiting is a luxury reserved for the elite but managing director of the company, Simon Cundey, disagrees.

“It’s a functional piece. Gentlemen still feel very relaxed and reassured (wearing it) and happy to be in something that fits them,” says Cundey of its enduring appeal. “A lot of people in our world are very business orientated and don’t have much time to go traipsing around from shop to shop trying to find something that fits. It does cost but if you take the cost of it over ten years, which generally that’s what they should last, that’s a reasonable factor in price.”

In its basic form the suit has existed since the 17th Century, and in its contemporary form since the beginning of the 20th Century. The look has remained essentially constant and proliferated across the globe among the elite and then among ordinary men, and eventually among women adopting variants of the business suit.

Director of the Fashion Institute of Technology Museum in New York, Valerie Steele, believes the suit retains its enduring power “because I think it connotes modernity." She says: "I think that it looks modern, it looks efficient. Some would say it is functional, I think it’s more a case of: it carries connotations of modernity and functionalism and status.”

Someone who knows a thing or two about the origin of modern suits is fashion designer Sir Paul Smith who has dressed everyone from Pink Floyd and the Beatles to David Bowie.

You can just get on with business rather than having to consider the wearer’s background, where they come from - Martin Pel

“I wear a suit every day, even at the weekend,” says Smith. “I just find they really work for me,” he says from his studio in Covent Garden which has been open since 1979. He describes how, back then, the people who wore suits were businessmen or going to a wedding, funeral or a job interview. But thanks to Smith and other menswear designers like Giorgio Armani, the traditional suit began to change.

“[We] softened the suit up,” he says of the classic design, “softened the shoulder pads, made the suit more easy to wear because a lot of people were coming out of wearing a denim jacket with a zip up the front or a more casual item.” He says young men might come in to his shop looking for fabrics like chalk stripe but instead of having a white stripe running through it, it might have a lemon stripe.

But while Smith was busy making people stand out from the crowd, the classic suit remains. Martin Pel, curator of fashion at the Royal Pavilion in Brighton, calls it: “a great leveller, you can just get on with business rather than having to consider the wearer’s background, where they come from.”

Valerie Steele agrees: “There is a sense (that) if you’re wearing the suit, it disappears, there’s nothing conspicuous about you, you’re just dressed appropriately and I think that is very important.”

Steele points to the work of fashion historian Anne Hollander who suggests that “one reason for the longevity of the suit is that it suddenly idealises the body. So through padding in the shoulder, adjusting the proportions, you can create a facsimile of a good-looking body while also just generally veiling less good-looking bodies.”

During wartime, adopting this worker silhouette served a different role. In the 1940s women took over men’s roles and also adopted the masculine outline of the suit. Martin Pel explains, “it was utility and it was saying ‘let’s get on with what needs to be done’. Men are at war so women adopted the suit – they didn’t wear trousers; they wore skirts – so it was women getting on with business. It is a utilitarian garment but it is able to be so much more than just a utilitarian garment.”

Uniformity

But of course, historically, this utilitarian use and blending-in through clothing was also used to assert power. China’s Cultural Revolution in 1966 was a brutal attempt by Mao Zedong to forge a new type of country. Like other authoritarian rulers, Mao scrutinised the details of people’s daily lives; what they could read and see and say and even what they could wear.

And what they wore was known as the Mao suit, also known as the Sun Yat-sen uniform, after the first great nationalist revolutionary leader Dr Sun Yat-sen. The suit came in three colours – blue for peasant workers, grey for Communist officials and green for members of the People’s Liberation Army.

So, in modern day life in democratic, western civilisations, does the suit still have a role to play?

Simon Cundey feels that in business, by wearing a suit, a “gentlemen will feel more reassured that if you’re going to invest in something or meet and discuss a project together… it’s a sort of mark of respect you make the effort to take something serious in life.”

“I don’t think the suit will ever die,” says Martin Pel. “I think it’s such a great piece of design. Whether we wear it every day or whether we wear it on occasions, I don’t think it’s ever going to go away.”

And as Paul Smith says: “you can be 13 or 100 or a rock star or a schoolboy, there’ll always be a place for the suit.”

To comment on this story or anything else you have seen on BBC Capital, please head over to our Facebook page or message us on Twitter.

If you liked this story, sign up for the weekly bbc.com features newsletter called "If You Only Read 6 Things This Week". A handpicked selection of stories from BBC Future, Culture, Capital and Travel, delivered to your inbox every Friday.