In a cafe in central London on a Thursday afternoon, Mr Archie Maher has ice all over his trousers. This isn’t an accident: it’s part of a demonstration, showing how this particular pair of strides – made by Stone Island in the 1980s – change colour when they come into contact with cold, turning from a mustard yellow to a bright blue. “It’s amazing, isn’t it?” Maher says, marvelling.

This isn’t just a piece from his personal collection: with his business, Arco Maher, the 27-year-old south Londoner is a go-to seller, consultant and archivist within the world of technical sportswear.

Focused on clothes that go above and beyond the pieces you might go for a run in, technical sportswear revels in detail, fabrication and functions. These clothes make use of innovation in fashion to ensure their wearer is ready for anything.

They have a style that is simple, wearable and makes you look like an explorer even if your lifestyle is entirely urban. See, for example, the clean look of Arc’teryx, outerwear from The North Face and C.P. Company, Patagonia’s sustainably minded fleeces and – of course – Stone Island.

The Italian brand, with its compass insignia, turned 40 this year. Founded by Mr Massimo Osti in Milan in 1982, it stood out in the 1980s, among polished tailoring from the likes of Giorgio Armani.

Stone Island focused on fabric innovation and extreme functionality, often inspired by military and outdoorsy clothing. This level of geeky detail means it is a brand that attracts obsessives – and Maher is no exception.

“It’s in the DNA of the brand to find materials that you wouldn’t typically see in the fashion world,” he explains. “That just blows people’s minds – coats and jackets that change colour in a certain temperature change, a jacket made of metal mesh… It’s just fascinating.”

Today, Maher – a likeable character who is fond of the word “amazing” – is wearing a YMC sweater, Molly Goddard trousers and a vintage flowered neckerchief, accessorised with a Stone Island backpack. As seen in his MR PORTER shoot, he regularly mixes his beloved Stone Island pieces with things from Acne Studios, Jil Sander, Craig Green and Wales Bonner.

“I think wearing everything new doesn’t grab people’s attention that much,” he says. “It’s almost too slick and clean.” An aesthetic that combines innovation of the future with knowledge of the past seems like a sweet spot.

Maher has been collecting technical sportswear since he was a teenager and was drawn to Stone Island by watching videos of grime musicians such as Kano and Skepta, who often wore clothes from the brand. “I bought my first piece when I was 16 or 17, a striped Marina T-shirt from 1989,” he says. “I’ve still got it.”

This was just the start – Maher began to buy and sell pieces. “I remember really getting into it when I was at university,” he says. “I would get my student loan, and basically use it [to buy pieces] and live on nothing.”

The side hustle quickly turned into a fully-fledged business. Studying History of Art at University of Manchester, it’s fair to say he wasn’t immersed in Mr LS Lowry – “I was doing no work at uni, I spent all my time in the libraries just studying sportswear”.

He eventually left and his archive, Arco Maher, began in 2017. He currently has around 350 pieces from Stone Island, C.P. Company and other affiliated brands, some of which date back to 1982. The items are regularly lent to musicians, stylists and design teams around the world, shared to his 37k followers on Instagram, and sold to celebrity clients including Ms Kim Kardashian (she bought a pair of ski sunglasses) and Drake.

Maher says 1982-1994 is the best era of Stone Island, when Osti was designing, but he has become a victim of his own success when it comes to collecting. “It becomes harder to source those pieces,” he says. “I noticed these corduroy shirts designed in 1993 and there wasn’t any hype around them, so I started trying to collect every single product. Then they went from selling for 200 to 600 quid. It’s kind of exciting but it explodes in your face.”

He is still yet to score his grail pieces – the 1982 Zeltbahn Cape, a waterproof design that can be transformed into a tent, and the SS88 Raso Gommato Black Cover jacket, with removable visor.

The buzz of finding coveted pieces remains. “It’s a constant chase and that’s why it’s enjoyable,” he says. His hunt has seen Maher searching shut-down stores in Paris and Athenian basements. He says the “jackpot” is always “a guy who’s been collecting for years and years and his wife wants to clear out his wardrobe. It’s kind of evil at the same time, because they don’t really know the worth of those pieces.”

Part of the culture around Stone Island comes through the label’s popularity with football fans, particularly in the UK. Maher grew up as a Chelsea fan, first attending games with his dad when he was five or six. “[I don’t remember seeing it,] but I definitely did pick it up,” he says. “It’s those small things you see when you're growing up and it sits in the back of your mind.”

While some see this association as a negative – Stone Island has sometimes been painted as a brand that’s connected to hooliganism – Maher refutes that. “You can walk down any street and someone is wearing Stone Island, go to any estate,” he says. “I view that as positive because it shows Stone Island can be seen in so many different walks of life.”

It’s led to some moments of connection for him, too ­– such as when he wore one of the 1988 Ice Jackets that change colour, and come with a netted beekeeper type mask. He was stopped in the street. “You probably look a bit weird but it’s an amazing conversation starter,” he laughs.

Maher now spends most of his time working as a consultant and archivist, lending pieces to musicians and stylists for shoots, and to brands for research. “People saw on Instagram that I was sharing these clothes [and reached out],” he explains. “At the beginning, I wasn’t charging any money at all, because I was just honoured to be asked.”

Maher now has several regular clients in the streetwear and high fashion sectors, and he might, at some point, move into designing clothes himself.

Even if his consultancy removes him from the heart of “buy, sell” collector culture, Maher remains part of the community around Stone Island. He says a new generation have discovered Stone Island thanks to the book of archive pieces, Archivio ’982-’012, released for the 30th anniversary in 2012, and the series of collaborations between Stone Island and Supreme.

“I talk to around 20 to 30 people each day [on Instagram], who have just come to Stone Island or they’ve just bought their first vintage piece, and they want to have a conversation about it,” he says. “It’s incredibly time consuming, but at the same time, it’s kind of amazing because everyone seems excited.”

Drake – a notable Stone Island fan – slid into Maher’s DMs in 2017. “[He got in touch] saying he wants to buy some pieces,” he recalls. “I sent over 20 or 30 pieces to choose from and he was like, ‘OK, I just want to buy them all.’”

Maher then travelled with the items to the hip-hop star’s house in LA, an experience he describes as “surreal”. It turned out, however, that they had something in common. “What was so amazing,” says Maher “was his knowledge of Stone Island, the history, was incredible… he’s a details man.” The two remain in touch, hanging out on both sides of the Atlantic.

If Drake would render most people starstruck, Maher experienced this feeling when he met one of his heroes recently – Mr Carlo Rivetti, the CEO of Stone Island. It turned out to be the dream encounter. “He and his wife Sabina came up to me as if I was their lost child,” says Maher, dreamily. “They were like, ‘You’re part of the family. We love it [the archive], it’s just incredible.’ That was an amazing moment.”