Its name may be well known but, as the Helena May celebrates its centenary year, the club remains something of an enigma for many Hongkongers. The institution has been variously described as an exclusive ladies luncheon club, an important charitable body, a safe haven for young women, a harmless relic from the colonial era and even a "virgin's retreat".

The reality behind the impressive front doors of the distinctive purpose-built building at 35 Garden Road challenges many of the most deeply held and often misogynistic stereotypes about expatriate women in Hong Kong. The front doors that for decades were securely locked at 10.30pm to exclude unwanted (and wanted) male guests conceal a modern organisation for, and led by, women that has left an indelible mark on the social development of the city.

WHEN THE HELENA MAY INSTITUTE was opened, on September 12, 1916, by the wife of then governor Sir Henry May, it was a huge event, featured in all the local newspapers of the day, alongside coverage from Europe of the first world war.

"The formal opening was performed with a golden key in the presence of a large and representative gathering of ladies and gentlemen," reported the China Mail, which noted the speeches of principal benefactors Ho Kom-tong and Ellis Kadoorie, who donated HK$62,000 and HK$25,000, respectively. Ho's granddaughter, Sabrina Ho, is a current member who helps with tours of the club. Descendants of the May family will attend some of this year's centenary events, which include a children's fair, in June, and a "tux and tiara" ball, in September.

The use of Helena May's name was not just a courtesy, due to the status of Sir Henry. She was an invaluable source of charm and diplomacy for her husband - who, while widely regarded as a capable governor, was not over-endowed with charisma - but Helena also led the way in establishing the club, which had its origins in the Young Women's Christian Association (YWCA), the local branch of which had been founded in 1893 by British missionary Lucy Eyre but did not, at that time, provide accommodation.

The founders' original mission was to provide support for women and girls in Hong Kong, an aim that remains a guiding principle.

"This idea of us being an exclusive club is just wrong," says Tina Seib, the current chair of council, who is at pains to point out that it is part of the Helena May's mandate to preserve its heritage building ("The architectural equivalent of a dowager duchess," as the International Herald Tribune described it, and the exterior of which is a declared monument) and offer affordable accommodation to working women. That makes it subtly different from the clubs established in the colonial era that historian John Carroll describes as "the most important mechanism for affirming status and prestige".

The Helena May is rooted in issues brought forward by the social impact of the first world war, which Sir Henry made direct reference to in his speech at the opening.

"The war has shown in a remarkable manner what splendid work women can do in directions hitherto closed to their energies," he said, to a round of warm applause from the assembled notables. One of the practical effects of this new-found freedom was that European women began coming in significant numbers to Hong Kong to work and they needed safe, affordable accommodation in an intimidating city known for disease, vice and moral dissipation.

"Women came to work as secretaries, telephonists and accounts clerks. Stewardesses from the cruise liners were regular residents here in the 1920s and 1930s," says Diane O'Hare, former chair of council and now a member of the club's history committee. "Sure, the reason they came here was because they were looking for a husband, but they also came for a grand adventure in the exotic East … to live the dream," she adds, explaining that a "respectable address" was essential because potential employers would not look favourably on a girl residing in a seedy waterfront hotel in Wan Chai.

From day one, the Helena May also sought to attract paying social members, vying for the same type of woman as the Ladies Recreation Club, which had been established in 1884. In a letter written in 1921, Nan Severn, the wife of colonial secretary Claud Severn, explained how the Helena May had become a cross between a woman's club and the YWCA: "They like Peak people to use it as much as possible, as the more we use it, the more popular it is with other kinds of people."

However, although it may have taken some of the "big ladies" of the colonial elite - wives of the governor, chief secretary, bishop, etc - a while to grasp the fact, the club developed essentially as a facility for working women arriving in an unfamiliar place, a function it still performs.

"Women don't need a safe haven in the big bad city in the same way as they did in the past but there is still a great deal of camaraderie here," says Seib.

Many of the Helena May's earliest guests were influenced by a second European social trend: the suffragette movement, led in England by Emmeline Pankhurst. Women, including many of those coming to Hong Kong as expatriate wives, were increasingly independent minded, highly educated and socially conscious. A social and cultural centre with an impressive library, the Helena May quickly developed as a forum in which women could air their views and weigh in on social policy. For the first time, educated, well-travelled women with a conscience were getting stuck in and many of the men in charge did not like it one bit.

In her impeccably researched and highly amusing study of expatriate women, The Private Life of Old Hong Kong (1991), Susanna Hoe writes of the visit to the city in 1920 of feminist Sybil Neville-Rolfe, in her role as general secretary of the National Council for Combating Venereal Disease. Neville-Rolfe and a colleague were on an official fact-finding tour but were given the cold shoulder by the reactionary governor, Sir Reginald Stubbs, who pompously announced that he would not "allow his wife to identify herself in any way with the work of the commission".

Despite the official non-cooperation, according to Hoe, Neville-Rolfe's subsequent report stated she had been able to reach almost all the white women residents and, as a result, a training school had been established.

"Some 20 to 24 of the most responsible and educated women attended a course of eight lectures held at the Helena May," said the report.

That's remarkable because the governor's wife, Winefrid, would have been patron of the club by tradition and the lectures were a direct challenge of the ruling male elite.

Defying the masculine colonial orthodoxy could come at a price, though. Helena May members would have been aware of the case of Clara Haslewood, who arrived in Hong Kong in August 1919 with her husband, Hugh, a retired Royal Navy lieutenant-commander who had been appointed to run the naval chart depot, where the Admiralty stored and updated its marine maps. Clara had served as a nurse in the first world war and had worked for the abolition of forced prostitution. She was incensed by the mui tsai system, wherein young girls were sold as servants to Chinese families, some of them becoming sex slaves. The practice was then still tolerated in the colony and when, in November 1919, four newspapers published her letters opposing it, Stubbs was furious. He accused her of being of "unbalanced mind" and orchestrated the forced resignation of her husband. The couple left Hong Kong and continued their campaign from Britain.

"This example was quite likely common knowledge within the expat community and Helena May members even a decade later," says O'Hare.

The Helena May's social members had to support their husbands' careers for economic self-protection, if not out of loyalty, and this was evident during a long running campaign to prohibit both the mui tsai system and licensed prostitution.

"The pressure to end licensed prostitution came from three main sources: reformers in Britain, the League of Nations and a group of local European women," writes Carroll. The European reformers found a welcoming venue in the Helena May and, by the 1930s, the campaign was being led by one colourful protagonist in particular.

Stella Benson was an acerbic critic of what she called the "Hongkongeress" - "There are no women here, only ladies," wrote the novelist and feminist - and took up arms against sexual slavery and licensed prostitution while librarian at the Helena May. Benson considered colonial Hong Kong a society that was dominated by "tenth rate men and eleventh rate women". She deplored the common practice of Peak ladies sending their "coolies" to the club library to pick up two books at a time, as though they were grocery items. Nevertheless, the librarian loved the club.

"I remain devoted to the Helena May and should like to make it a good women's club, if not prevented by the up lifters," wrote Benson.

When she and co-campaigner Gladys Forster undertook research into sexual slavery for a local League of Nations sub-committee, which Forster was asked to chair in December 1930, their findings were harrowing.

"Mrs Forster came down to see me all morning and we drafted a letter to the governor. She was in a weepy mood, being a very tender hearted person; the little girl we found in the Tung Wah Hospital last summer has been used as a slave so drastically, and was infected so seriously with syphilis, that her eyes and nose were almost eaten away," wrote Benson.

Benson, Forster and others knew they were rocking the boat and, by doing so, running the risk of inflicting damage on their husbands' careers. Benson wrote that she was probably "safer than most" because her husband worked for the China Maritime Customs, which was beyond the governor's sphere of influence.

It would be misleading to paint the Helena May as a hotbed of feminist militancy - it was, after all, an establishment institution and we can't be sure to what extent the management was directly involved in these campaigns - but these examples do demonstrate that the influence of women on social policy was central to the club's values.

"The fact that members of the Helena May were interested in worldly issues is shown by their continuing support for International Women's Day," says O'Hare, producing a clipping from the China Mail, dated March 9, 1939, in which it is reported that more than 300 attended a Women's Day event at the club. A speech was presented by Dr Irene Ho Tung, the University of Hong Kong's first female medical graduate, and attendees were surprised by the appearance of Madame Sun Yat-sen, who was "keenly interested in the woman's point of view which was put forward at this meeting". Also present was a Mrs L. Thompson, an American who "went into the fundamentals of 'Women's Contribution to Moral Rearmament'."

From December 1941, during the Japanese occupation, imperial forces used the club building as a barracks and stables, and in the years immediately after the war, it was utilised by the British Royal Air Force.

The Helena May reopened to members on January 18, 1947.

"Within the next few weeks many old members rejoined and brought with them new members," writes Esther Morris, in the club's official history, which was published 10 years ago, to mark the 90th anniversary. During these post-war years, writes Morris, who joined the club in 1982, the resident "girls" were able to beat the strict 10.30pm curfew by tipping the nightwatchmen, known as Bruiser, HK$10 per month.

There are many colourful anecdotes of young men trying to penetrate the inner sanctum of the Helena May. In one incident, reported by Gwen Fisher in April 1954, two Americans broke in through the pantry and, when caught en route to a dormitory and asked to leave, "offered off-hand insults to Miss Matheson", the club manager.

The Helena May's fortunes have reflected the vicissitudes of Hong Kong over the decades - "The 1967 riots knocked the stuffing out of the club; we were down to a couple of hundred members," says O'Hare - and given its noble ambitions, it has not always enjoyed a happy relationship with the media. There have been various press reports of racism, snobbery and bullying down the years.

A China Mail story in June 1968 accused the club of discrimination after a Filipino woman had been refused residence, but the Helena May had long retained links to Chinese organisations and records show a Dorothy Woo served on the club council from 1947. Non-Europeans were not admitted as residents at that time, though, the club maintaining that the facilities (and residential fees of HK$600 a month) were simply better suited to white members, rather than there being an exclusion policy in place. Ng Mei-ling, a buyer for a department store, became probably the first non-European resident, on November 8, 1968.

Perhaps the most notorious media smear came in July 1972, when a China Mail journalist suggested the club was involved in a vice racket.

"The Virgin's Retreat doesn't sound a very promising haunt for a naval man who's just stepped off his ship after a few weeks at sea. But according to a little bird, the refined hostel for women which has earned this nickname for obvious reasons, in fact runs the most sophisticated call-girl system in town."

Solicitors were instructed to refute the allegation.

"People always seem to say nasty things about us but actually we're very nice," says O'Hare.

The club remains involved in social issues. It supports a number of women's causes, the current charity of the year being the Marycove Centre, in Aberdeen, and offers two annual scholarships for young women to study at the Hong Kong Academy for Performing Arts.

The membership is a lot more diverse now, though, with 40 per cent of the 1,034 current local members being male and all ethnic and social groups made welcome.

"When I was a child, I found the Helena May an intimidating place full of English ladies having tea," says Ho. "Today, the membership is diverse and active in the community, with lots of working women like myself."

Well-appointed studio apartments in the court building - which can be used by couples nowadays - offer a good-value alternative in sociable surroundings to hotels on the island, there is no curfew and the wife of the city's leader no longer reads all the new books in the library, rejecting those that are "unsuitable" because they contain references to kissing, cuddling or something more salacious. Club manager Betty Simpson estimates the club stages about 50 weddings a year in addition to hosting cultural events.

"We still have female-only accommodation in the main building and our guests range from backpackers to high-powered business professionals," says Simpson, and when guided up the stairs past the old brass speaking-trumpet, through which resident girls could talk to their guests at a safe distance, there is still a sense of entering forbidden territory.

Diana Rose has been a resident on the second floor for about four years. She found, like thousands of women before her, that the Helena May suited her needs perfectly when she returned to Hong Kong from California.

"It's a lot more social than living in some grotty 350 sq ft flat with brown doors," says the tutor and editor, who is now a council member for food and beverage.

At a centenary launch event on Wednesday, Canto-pop singer and actress Gigi Leung Wing-kei will be unveiled as the new club ambassador. Leung is locally born, glamorous, successful and a mother with a well-publicised social conscience. She is so perfectly qualified to be the face of the Helena May in 2016, cynics might assume she was selected by an expensive PR agency as part of a carefully planned image makeover.

The truth is that Leung is a former member of the club and Ruth Kan, a current council member, happened to know the star through her work in television marketing.

"I just hope that more people can appreciate the importance of the heritage of the Helena May and of women's welfare in the development of Hong Kong," says Leung.

The event on Wednesday will not be a black tie gala, dripping with VIPs, expensive tickets and plenty of expatriate egos. Instead, in typical Helena May style, it will involve lunch and some line dancing, followed by a "cutting the cake ceremony".

Says Seib, "We just think of ourselves as a humble club run by women for women."