Last month I attended my nephew's Confirmation and, instead of wearing a suit, I took the seemingly contentious 'smart casual' route. This consisted of boot-cut suit pants, a fitted shirt, skinny tie and Converse runners.

I didn't give it a second thought, but the first thing my nephew's thirtysomething father -- my brother -- said to me was, 'What? You couldn't spring for a pair of shoes?' while shooting me a look that he would normally reserve for a clogged toilet or Liverpool supporters.

Being so hip and trendy, I tried to inform my square brother that this was 'the fashion'. After all, Mick Jagger was spotted wearing Reebok runners with a navy suit to a high society wedding recently, a less-formal style that has also been embraced by Dr Who star David Tennant, chef Marco Pierre White, and, heaven help us, even British Tory leader David 'Call Me Dave' Cameron.

Even more radical, Bolivian president Evo Morales is famous for turning up to meetings with other presidents and statesmen decked out in stripey jumpers, tennis shoes, light-coloured jackets and even jeans.

But my brother, being somewhat of a traditionalist, wasn't convinced. It's not his fault. The whole concept of 'smart casual' for men and women is often so vague that sartorial disputes over what's deemed an acceptable balance between formal and casual are inevitably going to arise.

Should I have gone for the conservative, formal look for the Confirmation? Or was my outfit just a minor example of how the idea of smart casual is being tested to its limits more and more at functions, parties and in the workplace?

It was decided that I should consult experts on both sides of the debate in order to get some answers, and my first port of call was the legendary tailor Louis Copeland on Capel Street in Dublin.

Suits are definitely back in vogue this year, influenced in part by the stylish 1960s-set drama series Mad Men, starring the dapper Jon Hamm.

I have to admit that any Morales-esque anti-establishment-style attitude I had was challenged when Louis gussied me up in a e1,300 Armani suit, coupled with a white shirt, Duchamp necktie and shiny brown shoes. Who said that money can't buy class?

"Once you've worn a good suit, it's very hard to go back," Louis tells me. "I think there has been a swing back to people wanting to dress up.

"Over the past few years people have been dressing down, but they find that they're not noticed. They don't stand out. When you see a fellow coming in a smart suit, with a nice tie, he sticks out.

"Some guys might rebel against the formal style a bit when they're younger, but after a couple of years they see sense.

"Guys are going for quality over quantity these days too. I've found that men don't mind paying extra for a suit because they know that in the long run it will probably be the cheapest outfit they will ever buy."

As for dressing more casually, Louis has a definite idea of what is acceptable and what's not. "I think you should go for a nice pair of Chino trousers/ slacks, always with a long sleeve shirt, tie is optional, and always with a pair of shoes, never trainers. Unless you're one of the Gallagher brothers! My biggest no-no in terms of smart casual is a pair of shorts. In my mind, they are never acceptable unless you're on the beach."

After reluctantly handing back the suit, it was time to hightail it across the Liffey to the flagship store of Topman on Grafton Street.

Once there, stylists Mandy and Dean dolled me up using a more fluid understanding of smart casual, namely dark skinny jeans, a waistcoat over a white polo shirt, knitted tie, and black plimsolls, topped with a pair of dark shades.

It might not be wedding material, but I thought the outfit was perfectly acceptable in a modern smart casual context.

Topman's design director Gordon Richardson agrees, and states that the term 'smart casual' is rapidly becoming redundant in today's fashion climate.

"I find that the young fashion-conscious consumer's aim is to look cool regardless of situation or occasion," he says.

"Now they have an unheard of choice of fashion trends to tap into, in accordance with their particular tribal allegiances, be it indie boy, skater kid, emo, and so on. These guys are in an enviable position of being able to express their own individuality like no previous generation before them, breaking down social dress codes in their fashion wake. When it comes to dressing, they like to subvert the norm as a DJ would when mixing tracks.

"Today, you see the cardigan replacing a more structured jacket, waistcoats being worn as a fashion item in their own right, trainers with suits, trilbies on the beach, gingham shirts and skinny ties under suits and bow ties with polo shirts."

So it seems the outfit choice for my nephew's Confirmation can at least be justified in the context of peer trends, if not in my brother's eyes.

Then again, as Richardson puts it: "That style may be frowned upon by the older generations, but that, after all, is the point."

- Declan Cashin