From socks to frocks - what our fashion choices reveal about us

Prof Mair says clothes provide a unique way of expressing ourselves. She looked at some of our best-known personalities and decoded what their fashion choices say about them.

The Taoiseach may have the appearance of a conservative, but his fondness for showing off a zany sock is a signal of his more "quirky" personality, she says. "Wearing a well-fitting, tailored suit - as Leo Varadkar does - is associated with being reliable, professional and conscientious. His clothes are appropriate for his role as leader of the country and give a professional image.

"He shows his personality through his socks; he's showing off his quirkiness, which is very cool. Socks for men can be like shoes for women. You might see a woman who looks traditional in a business suit and then look down and see these incredible shoes and go, 'wow'."

Ali Hewson and Bono adopt a "mirroring" style when it comes to clothes - when she's smart, casual or formal, he is too. "They know their style and consider the occasion and the context. They may choose different silhouettes, but the style is the same."

Ali - who founded ethical fashion brand Edun - always wears black. "There are only a few pictures of her wearing a deep cerise or midnight blue, but mainly black. She works in fashion: people who work in fashion wear black, it's like the uniform. Black, loose and androgynous, which is Ali's style, is very much fashion."

Bono is "really down to earth; he has never changed his style. He dresses like a rock star and he carries it well. He looks genuine, and he's an activist, so he's not flamboyant in his clothes. He doesn't seem excessive, which given his activism would be inappropriate."

Controversial soccer legend and television pundit Roy Keane's occasional adoption of corduroy and a beard shows he's moving from rebel to reliable. But he's still an alpha male.

Professor Mair said: "It's a real country look. Perhaps he is trying to show a more reliable, fatherly side. Beards are very fashionable, and definitely alpha male - fullness and thickness suggests plenty of testosterone, which women find attractive."

Mary-Lou McDonald's frequent choice of red as a colour is a sign of a person who feels attractive, and as a result, is attractive to others.

The Sinn Fein Leader uses colour to convey a message - often through colourful jackets that match the event. "Colours are interpreted according to socio-cultural learning and we see her in green jackets, which is patriotic, or red, which is for winning."

She is also fond of red lipstick. "Red is attractive. It is associated with being perceived as attractive and then people see us as more attractive. If you're on a date wearing red, men will spend more money on you; they tip waitresses more if they're wearing red. Even on a dating website, a red background will result in more hits. If you want to be more attractive, wear red, or red lipstick."

Mair chose actresses Sharon Horgan and Amy Huberman as Irish women of distinct and confident style. She singled out Amy's choice of outfit while meeting with Prince Harry and Meghan recently.

She said of the gold dress: "It's gorgeous. It's special. Her usual feminine style, with a richer edge to it for the occasion. It's an event dress, suitable for royalty."

Catastrophe star Horgan's clothes show she is "vibrant, fun, dynamic and definitely her own person. She is obviously confident, a woman who clearly knows who she is".

Roisin Murphy's style is beyond fashion and into performance. "She is interesting, multi-talented and has lots of sides to her. Music is just one way of expressing who she is, clothes are another and she combines the two."

Murphy is what Mair describes as the opposite of "twinning" - a new fashion trend where you copy the exact look of a celebrity, or dress the same as a friend.

Professor Mair says it is "a sad indictment of us losing our own identities". She is backing the #maxximumstyle campaign, that celebrates unique personal style, which is good for our self-esteem and wellbeing.

"Twinning is the opposite of individualism; where we all dress the same and look the same. I think it has come about through cosmetic surgery, where people are morphing into the one person.

"The entire concept of beauty is that beauty is rare, so if everyone looks the same, what is beautiful?"

It's a trend that has come about due to social media, where people clamour to get "likes" and is an easy option for those too lazy to think about style. It s welcomed by unimaginative clothing companies, as they can just reproduce the look copied directly from Rihanna, Kendall Jenner or the current celebrity of the moment.

"It's good to take a little bit of the style, and adapt it to your own individuality, but not direct copying: that's not creative and it's too hard to maintain. Mindlessly copying the exact outfit of a Kardashian is the antithesis of style and art and there is no sense of empowerment or achievement about it. It's better for our mental health to be confident in our own identities."

"Wear our own style, something you feel comfortable and confident enough in to walk across a crowded room. Your ideas are just as good. It's too hard to keep up the pretence of being someone else."

Prof Mair is in Ireland for a campaign by department store TK Maxx on the empowerment potential of individual personal style.