“That same day we were inspired by the idea of starting a designer swimwear label that was more affordable and accessible, so it pretty much started from there.”

The duo quit their jobs, sold their possessions and moved from Australia to Hong Kong to be closer to the supply chain. But money was tight, and they were reduced to packing orders from their tiny flat in Central.

“We moved to Hong Kong to focus 100 per cent on the business. It was a relatively easy move because Hong Kong’s very central from a global logistics point of view. We wanted to ensure that our products reached our customers quickly!

“We were down to our last few hundred dollars,” says Deering, who worked in e-retail. Ellis is a former Australian rules football player.

“We swallowed our pride and asked some friends to lend us a small amount of money to get our first production of Triangl under way. I guess the rest is history.”

Today the brand continues to take the swimwear industry by storm. And it’s all been achieved without spending a cent on advertising, instead relying on photo-sharing platforms for exposure (Triangl’s Instagram account has three million followers).

Triangl sent bikinis to Instagram stars such as Beyonce and Miley Cyrus, but it was a post on Instagram in 2013 by reality star and Kim Kardashian’s half-sister Kendall Jenner that really pushed up sales in the US, their strongest market. However, Deering is quick to point out that Triangl never pays for promotions or collaborations.

“Girls who wear our bikinis genuinely love the brand. As we had close to zero marketing budget in the beginning we had to be more creative and think of cost effective ways to market our product – so social media was where we headed.

“Instagram has been pivotal to our success – we love how we can directly communicate with our customers. It’s been crucial to the growth of our brand and is something we really value.”

Hong Kong-based fashion designer Marie France Van Damme also has good reason to toast the bikini’s birthday – and the power of celebrity.

Her business got a boost when Hollywood star Charlize Theron wore a silver metallic bikini designed by Van Damme in a Vogue shoot photographed by Mario Testino in May, 2014.

“Sales went through the roof,” says Canadian-born Van Damme, who moved to Hong Kong in the 1980s to start her manufacturing company specialising in women’s wear. She has a stand-alone store in Central’s IFC.

Van Damme says she sells about 10 bikinis for every one one-piece swimsuit, but admits a bikini “is the hardest thing I have ever designed”.

“It’s more popular than a one-piece swimsuit but I realised that if the top fits nicely then the bottoms often fit terribly.

“I stared at many ladies’ bottoms during a Phuket vacation, came home, and worked with my pattern maker to make the perfect triangle bikini,” she says.

“The fit of my first bikini was not good. Nor was the second, or third ... I have never spent so many hours fitting, correcting, pinning ... that small piece of clothing has been the most difficult garment to produce!”

The designer says there’s nothing worse than seeing a woman at the beach looking uncomfortable in her bikini, the bottom being too small or the top needing to be readjusted.

A staple of summer holidays, the bikini made its public debut in 1946 when 19-year-old nude dancer Micheline Bernardini modelled it while holding a matchbox in 1946. The press and public were shocked – it was the first time a wearer’s navel had been revealed.

Since then it has come to mean different things to different people.

“The invention of the bikini is a matter of dispute among fashion historians and commentators, as fashion couturier and sportswear designer Jacques Heim and mechanical engineer Louis Reard both claim to have created the bikini for the beaches of Cannes in the summer of 1947,” says Anne Peirson-Smith of City University of Hong Kong.

“Yet Reard was the only one to have patented the design, which was a basic construction of two triangles at the top to cover the breasts in a halter neck style and two triangles at the bottom, all held together and attached to the body with string-like ties.

He named this radical invention after the atomic bomb that had recently been exploded at Bikini Atoll in a series of US military nuclear tests, believing that this innovative design would have a similar explosive impact where it was worn.”

For Van Damme the bikini symbolises freedom and girl power.

“This two-piece bathing suit created a lot of controversy in the puritanical 1950s. Many people found it scandalous for a woman to wear a bikini . Finally it became accepted in ‘Western society’. It’s about women’s emancipation, La liberte de la femme!

“We all remember Brigitte Bardot at the Film Festival in Cannes in the ’50s – the bikini turned several actresses into sex symbols.”

Other celebrated roles in popular culture include a catchy 1960 Brian Hyland song, Itsy Bitsy Teenie Weenie Yellow Polka Dot Bikini.

“That tune is credited with creating acceptance for the bikini and making it more mainstream, alongside possibly the most famous early pop culture white bikini worn by Ursula Andress’ character Honey Ryder in the 1962 Bond film Dr No, which generated pure desire for the clothing item,” says Peirson-Smith.

The bikini became a Hollywood prop with stars Rita Hayworth, Ava Gardner, Ester Williams and Marilyn Monroe wearing one, prompting Margit Fellegi for Cole of California and Catalina to mass manufacture bikinis complete with deep-cut necklines and bare midriffs, so audiences could copy their idols.

“In the 1960s the bikini became standard beachwear and was associated with California and San Tropez.”

She also cites a time when China Airlines required aspiring female cabin crew to dress in a bikini as part of the interview process and a Vietnamese airline featuring a bikini show by female cabin crew en route to beach destinations.

Peirson-Smith says the bikini has played a significant social and cultural role as a mirror of body consciousness, moral concerns and sexual attitudes, its daring, revelatory design challenging moral codes. It took the minimally clothed female body into the public gaze both as a site of power and a spectacle to be looked at and judged.