Drawing ladies in ball-gowns on his books at O'Connell's, one of Dublin's tough Christian Brothers schools, was a risky hobby for Finglas lad Peter O'Brien.
But the designer escaped unscathed and, after leaving school early, went on to achieve the stuff of any fledging designer's dreams.
When he left school following his Inter Cert exams, O'Brien took up a job as a window dresser at Best menswear, which he followed with a spell at Arnotts. Then, at 19, he moved to London and worked for Marshall & Snelgrove - now Debenhams - before securing a place at the renowned Saint Martins School of Art. Upon completing a degree in fashion design, the young O'Brien headed off to New York to study at the Parsons School of Design.
After that, he made the move to Paris, starting out at Christian Dior, where he worked under the legendary Marc Bohan, before moving to Givenchy. He later was a senior designer at Chloé and held the position of creative director at Rochas for 12 years.
O'Brien, now 66, insists that as a working-class boy growing up in a council house on Casement Grove in Finglas, he never had his eye on "being rich and being famous".
In 2004, he moved back to the city he grew up in, where he now divides his time between lecturing and designing. It was a year later, in 2005, that he had his first foray into designing for theatre, going on to create costumes for numerous Irish theatre productions - most recently for The Gate's hugely popular The Great Gatsby. He also designs collections for Dunnes Stores and there are private commissions, too.
It must have been a seismic change from Finglas to Avenue Montaigne and the most stylish fashion districts of the City of Light?
"In the beginning, I was kind of amazed by it. But it's only now, in retrospect, that I think I had this amazing life."
Looking back, O'Brien admits that while he has always been really good at designing dresses, he was sometimes not so great at having a career.
"I never had that killer instinct and I kind of wish I had been born with it," he tells me. "Some people have no self-doubt. None. And if you marry that with ambition, you can kind of rule the world. There are people who are not particularly brilliant at what they do, but they do not have one gramme of self-doubt, and that married to real ambition will take you anywhere. I kind of wish I'd had that."
The French fashion houses he worked at may still exist, but they are no longer helmed by their namesake designer.
"When I went to Paris first, the name above the door tended to be the name behind the design desk. That's not the case anymore. Once upon a time, when Mr Givenchy was at Givenchy, Monsieur Valentino was at Valentino, Christian Lacroix was at Christian Lacroix, but now, because all of these companies are owned by two huge corporations, there often tends to be a revolving door of designers. It's like Broadway - you could open a show because you had Mary Martin or Ethel Merman and you would get bums on seats because of that. Nowadays, it's a marketing tool. No one really cares who plays the lead in Phantom or Les Mis. It is the logo, it's the brand - and it's the same in fashion."
O'Brien smiles as he recounts the story of doing a fashion shoot with fellow designer Karl Lagerfeld. "He was photographing all of us in his studio and we had to wear white shirts and black jackets. I put one on and he commented, 'It's very white, very white, get maquillage [make-up],' to which I said, 'Karl, please do not put make-up on me. I will look like Dirk Bogarde in Death in Venice.' Karl laughed... I still have that photograph somewhere at home. It appeared in French Vogue in 2001."
During his time working in the studio at Dior with Marc Bohan, his work mainly involved sketching away dutifully.
"It was very formal. Mr Bohan would say he was doing a collection based on, say, 'chinoiserie', and we would do our ideas and then hand them in at the end of the day.
"At first, I lived in a tiny flat on Avenue Parmentier. It's now quite a cool neighbourhood but it really wasn't back then. A bird got in one day and we thought we were in an Alfred Hitchcock movie."
O'Brien tells me that his French was "terrible with a broad Irish accent".
"It got better as time went on. You are spoilt in the fashion business because so many people speak English. I liked living there. The food is really nice, the city is beautiful, but there are too many tourists." But it was not, as one might have imagined, party central for the young designer.
"I never went to parties. I am kind of oddly anti-social. I was always in the studio until nine or 10 at night, fiddling around with crêpe de chine and taffeta. But I had dinner all the time at Davé. There was never a menu but you saw everyone there, from Marc Jacobs to Yves Saint Laurent to Catherine Deneuve. It really was like my canteen - I went there a lot."
O'Brien recalls the night his good friend, the actress and singer Patti LuPone, got up in the Zinq bar. "She sang 'Don't Cry for Me Argentina' for about 45 very happy homosexuals who all died and went to heaven. That was one of those nights. There were millions of nights like that. I sometimes wish I'd kept a journal or a diary because it would have made an interesting book, I think."
Born in London to Irish parents, O'Brien and his family returned to Ireland when he was a child and lived initially in Dún Laoghaire. Raised by his mum, Muriel, after his parents separated, O'Brien grew up with his three brothers and one sister in a very close-knit family.
He describes himself as having been "quite solitary but not in any way unhappy".
"I was very self-sufficient and I loved to read. I drew all the time. I never analysed it. I was always intrigued by clothes and women's clothes, not that I wanted to wear them or to be one. I remember my granny had this 1920s sequinned dress and thinking it was magical."
Growing up, O'Brien says, they were not exposed to sexuality the way kids are today so it may not have crossed his mind that he might be gay until he was 13 or 14.
"I was kind of blithely unaware and then it sort of dawned on me one day and I thought, 'That's kind of fabulous, I'll be eccentric.' I was lucky. I have a brilliant family. It was never an issue."
O'Brien currently lectures on costume on the Design for Stage and Screen course at IADT in Dún Laoghaire. He was invited to help out by the film costume designer Eimer Ní Mhaoldomhnaigh. That was five years ago. Did he ever think that the boy who left school early would end up a lecturer?
"No, never. I always wanted to do it but never knew how. I am not an academic but because of the experience I've had, and because I had this odd career that kind of veered slightly to the left into theatre unexpectedly, I think it kind of qualifies me. I think I have an added layer that I really know about clothes. I have worked in Paris, I've seen things and I can tell them about - for example, late 20th-century fashion, because for them it's a thousand years ago."
It is absolutely clear that O'Brien loves teaching; his eyes flash with excitement when talking on the subject.
"Alan Bennett says in his play The History Boys that if you know something or you have something that's kind of specific to you and is valuable - and I think I've had an amazing experience in fashion - you have to pass the parcel on. Oscar Hammerstein wrote in a song in The King and I, "If you become a teacher, by your pupils you'll be taught," and it's so true. I get so much from the kids. There's a wonderful thing about youth. It's the sense of possibility which, alas, we lose a bit when we get older. We get cynical and a bit jaded, and if we are realistic, the possibilities become more limited so there's this wonderful energy that they have.
"I'm a dinosaur, you know, so I think it's my duty to the ones who are interested and want to know to pass it on. It mightn't be very cool but Lagerfeld always said that if you don't know about the past and the design, how can you design the future?
"Consolata Boyle, the great Irish designer, came into the college one day and when asked by a student how they could become a better designer, she advised them to close their laptops, go to museums and galleries, look at paintings, see films, and not just the latest blockbuster, go to the theatre and read books.
"I wanted to stand up and cheer because the more stuff you have in here," he says, pointing at his head, "the better designer you are. The whole problem with instant knowledge is that they all end up with the same references because they will go to Google and Pinterest and you often find there is an overlap, so I try and 'do a Consolata' on them."
But age does not always confer wisdom, O'Brien insists.
"There's all the nonsense that as you get old, you get wise, but it just becomes more and more impenetrable as you get older. The questions that keep people awake at night, no one escapes, no one gets away scot-free. We all have to deal with loss, grief, death, ageing. Everything is temporary and it takes, you know, 60 years to realise that."
I am curious to find out how France shaped him, if he brought home any of their traits with him.
"The French have a hatred of anything 'endimanché', which is to be 'Sundayed up'. You know, the people who get all dressed up for the races. I certainly inherited that; I like quiet, invisible drama.
"When I came back to Ireland in 2004, it was the height of the Celtic Tiger. Ladies in Paris dress with a little cashmere sweater and a pair of chinos. They might add a flat pair of Ferragamos and maybe a slightly bashed-up Hermès bag that had belonged to their grandmother, possibly a touch of mascara. I came home and I'd go to the Four Seasons and people would be wearing beaded evening gowns at 12 in the afternoon! It was a real culture shock. I'm not approving or disapproving. It was just very surprising," says Peter.
Last year was a tough one for the O'Brien clan as they lost their mum in December. The house in Finglas feels very empty without her, he says.
"I miss Mam and I still talk to her, which may sound mad. Since Mam died, you just don't know do you have 10 minutes or do you have 10 weeks or 10 years left? Her death has made me think that life lasts for a blink of an eyelid. It's so clichéd but all you can do is grab every moment."
Reminiscing about his mum, O'Brien recalls how she used to chastise him for spending his money.
"I used to buy brooches and she used to say, 'Don't show me that. You should be buying a flat. You should be a millionaire by now. You don't need another brooch.' We used to laugh about it," he says.
Speaking of brooches, I admire the one he has pinned to his lapel.
"My lovely other half got it for me for Valentine's Day," he tells me. The designer is obsessively private about his personal life and prefers not to talk about his relationships. He has in the past referred to a relationship in New York that "crashed and burned". Another previous partner is now a very good friend. O'Brien says they were better as friends than partners.
Nowadays, if buying brooches is a guilty pleasure, then collecting books is a passion for the designer. Two walls of the living room in his Dublin 4 flat are lined with hundreds of titles. "They are breeding," he laughs.
A keen cook, you'll find him conjuring up a meal in his small kitchen. He does a very good chicken with tarragon, tomatoes and white wine, he tells me. Immediately after our photoshoot, he's off to buy the ingredients to make dinner that night for his dear friend, actress Ingrid Craigie.
The designer describes himself as very undisciplined.
"I wish I was one of these really disciplined people," he says. "I could while away forever looking at books or sorting out a drawer with photographs. If I was disciplined, I would be fitter and would exercise more.
"I don't smoke anymore. I don't even have the odd sneaky one. I used to have the odd Marlboro Light on first nights at the theatre. I barely drink anymore. I remember being 40 and thinking that when I get to 50, life will be horrible because there will be no joy, no pleasure. What can you enjoy when you're 50?
"I met Anjelica Huston at a party and I was being a total fanboy. She said she got sad when she didn't get roles and put it down to not being cute anymore. A wise friend told her, 'Anjelica, when you get to our age, you can't be cute, you have to be magnificent'. And she's right."
O'Brien tells me he recently went to see Oscar-winning South Korean film Parasite. "It's really good and I actually saw my first Tarantino film, Once Upon a Time in Hollywood, and loved it. I closed my eyes for the last five minutes but I did love it."
A longtime cinephile, in 2013 he was costume designer on the film The Price of Desire, which was based on the life of Irish furniture designer and architect Eileen Gray. It is this love of film, which no doubt feeds into his work as a costume designer for the big screen and stage, that will see O'Brien make an appearance at the upcoming Dublin International Film Festival. He will be talking about his passion for cinema, as well as some of the films that have influenced his career (see panel, right).
Is there anyone from that world that he would have liked to have met?
"Bette Davis. She was really smart. A lot of the movies she made were kind of quite soapish, very over the top, very kitchen sink, but she brought such truth and integrity. She was a brilliant actress."
As well as books and brooches, unsurprisingly he used to collect fabrics for his own archive but has had to stop because they just take up too much space.
"I've got stricter with myself about collecting things because there is no room in my one-bedroom flat. I have a lock-up. There's lots of taffeta skirts languishing there, which I think I should give to a museum because they will just disintegrate. I will probably give them to the museum at Collins Barracks or The Hunt Museum in Limerick."
Passionate about colour, O'Brien declares his love for wearing navy and black together. "I love a dark, dark bottle green with Holy Mary blue: it's so gorgeous. It's that pale blue that New York policemen's shirts are in, but paler. With dark bottle green, it is ravishing. I also think chocolate brown with pale blue is gorgeous. Everyone says it's bad taste but I love red and pink together or orange and red."
When it comes to interiors, his flat is painted white. "The apartment of my dreams is actually Jasper Conran's flat in London. He's on Instagram and it's so gorgeous and his house in Wiltshire... oh my God. I have no interest in mid-century modern. I want Colefax & Fowler. I want chintz and needlepoint rugs."
If life has taught him anything, he says, it's to trust your intuition and never be led.
"Once I was doing a play, and an actress, whose costume was a taupey colour said to me, 'Oh no, I'm only good in pastels. I have to have pale blue or pale pink.' I caved in and I did her costume in pale blue and it was horrible. She looked like a dealer from Bermondsey market going to a wedding. It was awful. I should have just trusted my gut," he says.
There have been lots of career highs but the couturier says the one thing he would love to do is design costumes for A Little Night Music, the musical by his all-time favourite hero, Stephen Sondheim.
"I would love to do that. Listen, I just want to keep going. I want to die with my boots on and I'm hoping to have another 30 years." Speaking of mortality, I wonder if this man of fashion believes in God. "I would say I am optimistically agnostic," he says.
"I am so lucky. I have a roof over my head, plenty of food to eat; I can buy an occasional book and brooch. I don't have a penny in the bank, but who cares - you can't take it with you when you go. I get paid to do what I love. I think I am the luckiest man on the planet."