Image copyright Other Image caption In 2011, most men and women feel that the need for hats, ties, suits and furled umbrellas has waned slightly

On Fridays many dress down, but is the suit in general decline as the standard business wear?

Once upon a time British cities at rush hour were a sea of grey suits, bowler hats and umbrellas.

The contrast with today is stark. It's not just the arrival of women in the workforce that has changed things but the shift away from suits to smart casual, jeans and even in some quarters trainers, T-shirts and flip flops. For both sexes.

A recent poll of 2,000 British workers by online bank First Direct found that only one in 10 employees wears a suit every day, more than a third of staff opt for jeans and only 18% regularly wear a tie.

Earlier this year, UBS created brief uproar when it unveiled a 43-page dress code for staff. It soon backed down in the face of much mockery over its demand for women to wear skin coloured underwear and men to have monthly haircuts.

Image copyright bbc Image caption Watch The Apprentice and there are plenty of suits to be seen on men and women

But there were some unlikely defenders.

The Financial Times's work commentator Lucy Kellaway wrote in her column: "Clad in my sloppy flannel pyjamas and fleece dressing gown, I'm looking again at the UBS booklet and thinking how crisp those lovely shirts look and marvelling at the wisdom of the advice."

Rather than Big Brother as critics had claimed, it "smacks of big sister and a kindly, helpful one at that", she wrote.

However, Claire McCartney of the Chartered Institute of Personnel and Development, the professional body for human resources practitioners, says such prescriptive dress codes are becoming increasingly old-fashioned.

"There's definitely a tendency for employers to let their staff feel comfortable in what they are wearing," she says.

"Obviously there will always be limits to what is appropriate. But there is a wider acknowledgement that you don't have to wear a suit to be smart."

Cary Cooper, professor of organisational psychology at Lancaster University Management School, agrees that the world has moved on. Formality is out, and about time too.

The view from the workplace Humphrey, graphic designer: I wear trainers, jeans and a shirt or jumper, sometimes a T-shirt. Never a shirt and tie - I wouldn't want a job that demanded them. Jeans and combats used to be banned but now it's fine. Vernon, City analyst: Most days chinos and smart shirt but I wear a suit and tie when seeing clients. I like it to be relaxed. A couple of hedge funders like to show they can do what they like and wear ripped jeans. Louis, GP: I wear smart trousers and shirt. No suit or white coat as you might seem too authoritarian. No tie - they're unhygienic. Flip-flops, shorts, or visible thongs would be seen as unprofessional. Astrid, equity sales: A dress or skirt usually, definitely if I'm meeting clients. Sometimes jeans. In general men have trousers that are far too short, bad shoes and awful hair styles. Women wear "sexy" outfits with fishnet tights and low cut tops. Barry, IT manager: Black suit trousers and smart shirt. Things have loosened up. About 15 years ago a manager of mine came in wearing flip flops - it severely damaged her credibility. I doubt that would happen these days. Francesca, corporate lawyer: 'Business casual' is the order of the day - skirts/trousers with tops, or a dress. No suits/ties necessary unless you have a client meeting. But some take it really seriously and wear a suit all the time. Samantha, teacher: I wear smart grey/black trousers with a V-necked top or casual blouse. Jacket is only for parents' evening and not always then. The men all wear ties and suit trousers but lots wear jumpers instead of jackets. In summer I wear flowery skirts and flip flops if I can get away with it. Names have been changed.

"Even in the City, people are wearing suits but no ties. They aren't coming in with jeans but smart casual."

Many professions have been "dress down" for decades but the trend in financial services began on Wall Street with dress down Friday about 15 years ago, he believes." The objective was to let staff get on with paperwork on a Friday and wind down to the weekend. It led people to question why they needed to wear a suit in the first place."

But there'll be a suit hanging there and a tie in a drawer in case they have to go and meet clients, he says. But doesn't this rush towards chinos, shirts and jumpers signal a lowering of the tone and a loss of focus?

"I disagree," says Prof Cooper. "There's no definitive research on the effect of dress on productivity. But I'd be surprised if we didn't find that smart casual saw productivity rise. The more informal an office - as long as it's not slovenly - the better the communication. It's about making the office less stressful."

While the suit may survive, Prof Cooper believes the tie has had its day.

"What is the point of a tie? It's the weirdest thing. If someone from Mars went into an office the first question they'd ask is 'what's that thing round your neck?"

Suits were once the unimaginative uniform of middle-aged men, but today some argue it's the casual look that smacks of blandness. The artists Gilbert & George, synonymous with smart, tailored suits, certainly think so.

In an interview with the Evening Standard in 2009, Gilbert said: "We are more offended by blue jeans than anything else. They are appalling. It's a uniform," before George adding: "It's the fear of standing out. The fear of being different."

And Fiona Allison, head of design at tailors Jermyn Street Design, says the suit is something we jettison at our peril. "What's good about the suit is you get the uniformity of everyone looking smart. And if you look professional you act professional. I think it's a shame more people are going to work in what they wear at the weekend."

Image copyright Getty Images Image caption It is possible to look un-businesslike in a suit

Some of her clients have asked for suits that tone down the formality but are still smart. So for a mobile phone operator she designed a smart suit to go with a polo shirt, while staff at a new boutique hotel wear a suit, trainers, and no tie.

Informality is not a given though. The influence of uber-stylish Mad Men, set in a 1960s New York advertising firm, has prompted a nostalgia for a time when men and women dressed smart and sassy.

Women's work wear has definitely got smarter while men's suits - when they choose to wear them - are getting sharper, she says. "We find our clients asking for women to be in a dress rather than shirt and skirt. It's more feminine because it shows off their figure. And men are getting more fussy about suits - nowadays it's normally slimcut like in Mad Men."

Dressing down is the easy option but we risk losing something precious, argues Alex Bilmes, editor of Esquire magazine. And too many workers are mixing up the idea of casual with sloppy, he warns.

"The downside is that everyone dresses scruffy now as if they're about to pop out to Superdrug. People are taking 'relaxed' too far to include wearing baggie jeans and track suit bottoms."

Clothes change attitude "We use clothes to say 'I mean business'. In investment banking you're there to make money for the company. That's very different to a creative environment, where you can be who you are, let your creativity go and not be constrained." The good thing about having a dress code is that it allows a clear separation between work and home, she argues. "People use clothes to reflect their mood. So when you get home from work, you come in, get out of your work things and put on your slob gear and relax. It's that demarcation between work and play."

Some professions like waiters, policemen and lawyers still understand the value of looking the part, he says.

"They're not stuck in the past, they know it's reassuring to people to look smart. If you needed a lawyer, went down to chambers to find one wearing shorts, a T-shirt with a logo and battered trainers, are you going to choose him?"

It's not all doom and gloom though. After a malaise in the 80s and 90s, formal styles are back in vogue with a "real buzz" around the traditional tailoring of Savile Row and Jermyn Street, he says. Men hoping to climb the career ladder would be wise to go back to classic English tailoring, he says.

"If you put on a tailored suit and pressed shirt you are putting on a suit of armour. You will walk a bit straighter and taller and people will take you more seriously."