Nikki Roberts is someone a teacher might call a good “all-rounder”: smart, pretty, lots of friends. Aged 31, she is also a far cry from your typical Freemason. But that, if the Federation of the International Order of Co-Freemasonry has its way, is about to change.

Forget secretive circles of white-haired men locking fingers in strange handshakes, they say. A British branch is in the throes of a thoroughly modern recruitment drive. It is using Facebook and Twitter to sign up new members, particularly young women, to its society.

“A lot of people have misconceptions about what Masonry is,” Ms Roberts says. Not surprising, given that for centuries members of this traditionally male club have refused to divulge what goes on behind closed doors in meetings and ceremonies. “I can say that it [the Freemasons] is an association, a fellowship if you like, dictated by a system of morals, with lot of symbols and philosophy...” Roberts explains. She compares it to an “occult”: “You need to believe in a divine intelligence or supreme being.”

Since joining the Freemasons five years ago, Roberts says her life has been transformed. “I gave up a lucrative job in the City and now I work in health and social care, something more rewarding,” she says. While cohorts at her lodge (one of the only mixed gender orders in the world, the British Federation) range from party-planners to nurses – many of them female – there are other common elements among members, she says. “The kind of people it draws are interested in being good people; we have respect for laws, we like giving to charity... we live by certain morals.” It is a “life-long commitment”, she adds.

The biggest misconception, Roberts says, is that women are not suited to joining the club. “People choose the Masons in order to become more aware and to awaken areas of their mind to their true nature; women, being naturally nurturing and intuitive, are particularly responsive to that.” That, however, is a matter of opinion. Ask Ken Kirk, 86, a former policeman and a member of the strictly-male United Grand Lodge of England and the answer is clear: “Mixed gender orders? Absurd.”

At first glance, Hexagon House, the British Federation’s Masonic headquarters in Surrey, does little to shift the fusty image. Inside this Surbiton base-camp, the 21st century seems a world away. The hallway is stuffed full of archaic artefacts, such as one might expect from a fraternal system dating back 500 years (the first clubs were recorded in Scotland in the late 16th century): ceremonial firing glasses, brass etchings and silk wall-hangings adorned with obscure symbols.

Follow the carved wooden staircase to the second floor, however, and there are small signs that that this particular order is trying to embrace the modern world.

On the shelves, alongside The Book of Mirdad and The House of the Temple (and a dark cloak hanging on the back of the door) is an A4 folder labelled “Website statistics” and a novelty mug with the logo “old masons never die / you’ll have to join to find out why”.

Worldwide, there are 6 million active Freemasons, with 2 million in the US and around 400,000 in Britain. At the moment the Federation of the International Order of Co-Freemasonry, founded by ideological polymath Annie Besant in 1902, has around 300 members (the majority of them women), and is one of the most progressive – and smaller – orders; many orders won’t let a young women through the door.

Conspiracy theories about what being a Freemason entails are rife. With famous alumni including Winston Churchill and Robbie Burns, the most common perception is that this is an elite club populated by powerful men. That is the dated image the Federation is seeking to change, explains Suzanne Jozefowicz, its secretary. “Masonic membership worldwide is dropping,” she says, and an image refresh is in order. “Freemasonry isn’t about the past, it is about the future, we need to reflect the world around us.”

Jozefowicz, who joined the British federation in 1984, is a suitably modern figurehead for the British Federation. Raised as a Catholic (“But I asked questions like ‘why isn’t God a woman?’ and never got an answer”), she worked as a school-teacher and then a rock musician before joining this, one of the few mixed-sex fellowships, in her twenties. “When confronted with challenges in life people invariably look for an explanation... [we] frequently turn to religion but more and more people are finding that doesn’t necessarily answer the sort of nagging ache within them to understand the purpose of life and what happens or not afterwards.”

So what does Freemasonry offer that is so different? “The natural processes of life come into play,” she says. “Masonry is experiential, it’s not something you can learn like you would for an exam... because Masonry is about your own personal search for truth.” Jozefowicz will confirm that there are various levels of membership, although not the existence of a supreme 33rd degree, which is one popular conspiracy.

“The most basic level is the apprentice, as found in the old building trades,” she says. “He would join with an expert craftsman and spend his time learning the basics; it was a very passive learning process...” Jozefowicz explains by way of analogy: “The apprentice then becomes a journeyman or, as we phrase it, a fellow of the craft, who is able to do work under the direction of the expert craftsman but isn’t yet able to go out of his own....”

At that point, he (or she) is given “some kind of broken token, half of which he would take, and the other half of which his mentor would keep; so the journeyman could go to different places but ultimately he was still bound to his teacher. “In the third and final degree, the secretary says, “the journeyman reaches his maturity and is able to go out as a recognised craftsman in his own right.” By which, she says, she also means “journeywoman”. “We have people of every background in our order,” she adds. “Now the majority are professionals, but we want to expand that out. We will open our door to anyone who knocks.”

Heading back downstairs to the library, past the loo (“It says Gentleman on the door but actually it is for women, too!”), Jozefowicz employs yet another analogy to explain what Freemasonry can bring to the contemporary citizen: “It is about gaining self-knowledge by way of practical instruments: there is the trowel, the gavel, the chisel, the ruler, the square... these are metaphorical instruments of measurement and calculation.”

Keeping their secrets secret is a Masonic priority. In order to ensure a low drop-out rate, candidates are thoroughly vetted; only once that has been done does the initiation begin.

At Hexagon House the magic happens in The Grand Temple room, replete with astrological symbols painted on the ceiling, there are wooden thrones surrounded by carved wooden objects and an organ. But what really goes on once the music starts and the incense has been lit?

“There is a handshake, yes,” Jozefowicz confirms. “But they are part of the things that are secret in each ceremony so [what they consist of] is one thing that I can’t disclose to you.” Even if she did, she says, the knowledge would be useless out of context: “It’s purely a means of recognition and generally speaking it’s only used within the lodge.”

What about the noose, which according to hearsay is placed around the inductee’s neck? “Let’s not call it a noose, let’s call it a cable-tow,” Jozefowicz says. “The significance is quite complex... [a similar rope] is used to moor a ship to its mooring, so it is a way of associating the person with the lodge, and also a symbol of something referred to as the silver cord... It is also is a reminder of the mortality of the individual because obviously if you get hung, you die.”

The rolled-up trouser leg? “For anything you go through in life there is always a specific preparation, and Masonry there is the same,” the secretary explains. “The practice varies, according to which obedience or which working or which lodge you go to... but always some of that is physical and some is mental. You will find in other orders that the rolled up trouser leg is part of that preparation. We tend not to get too distracted by things like that...”