Outspoken and a self-confessed tomboy, Guinevere van Seenus is not your average supermodel.And its her idiosyncrasies that have kept her at the top of her game for more than 20 years…

Guinevere van Seenus wants to set the record straight.While the models Wikipedia page might record her age as 39, she is in fact already 40.(Not one for parties, she celebrated last September with a small family dinner.)Im getting a little more comfortable as I get older; I didnt find my 20s easy at all, she says.Im happy to have some perspective because being in a business where everyone is really young is hard.

Her candour is surprising.But then again, van Seenus is something of an anomaly in fashion, having enjoyed a successful career for over 20 years.Shes worked with Tim Walker and Mario Testino, fronted campaigns for Prada, Jil Sander, Azzedine Alaïa, and Calvin Klein – and in March she starred in Dries Van Notens landmark 100th catwalk show, a celebration of womanhood with almost all the models cast over the age of 30.There is a resurgence of the industry wanting some unique individuals.Even with the younger girls, I see faces and personalities where they are 100 per cent their own, van Seenus says.

The self-confessed tomboy is certainly her own person.She brings her three-legged adopted stray mongrel Ashley on every shoot.And her signature style?Im really lazy about dressing.I think heels are super sexy but I have a hard time with them.

Her Dutch mother, a catalogue model who relocated to the States in the 1970s, first suggested modelling to her daughter when van Seenus was 12.But, when puberty hit, Things went sideways, not vertically, she smiles.A growth spurt at 14 led a Santa Barbara model agent to take her on, but her powerful features – alabaster skin and Vermeer hooded eyes – made her hard to pigeonhole.Castings were like Baywatch.Very, very commercial.Told that she had a weird face and strange body van Seenus returned home, defeated.But she couldnt shake the lure of the escape route that modelling offered:An adventure.Getting out of your hometown, finding something to focus on.

On a trip to Paris, aged 18, her fortunes changed thanks to a shoot with photographer Paolo Roversi.I went in for a Polaroid and I didnt know if he liked me – I was sure I was going home and that was it.And then I got booked for my first shoot– with Stella Tennant – for Italian Vogue.We were in the Galliano drippy dresses of the time.All of a sudden, things clicked and made sense.

Van Seenus became one of the gang during an era in fashion when individuality was the currency; strange, beautiful and boyish girls – such as Kate Moss, Stella Tennant, Rosemary Ferguson and Kristen McMenamy – were nipping at the heels of the glamazon supermodels.Even so, on occasion, van Seenus would walk on set and be mistaken for the make-up artist.Most of the time you were going into a world that was looking for a Cindy Crawford.

Shes retained her sanity by staying healthy – especially important after a bout of fibromyalgia in her early 20s, a condition that causes pain all over the body.A roster of boxing, ballet, spinning and Pilates keeps her in shape, shes in bed by 9pm most nights, uses apple-cider vinegar to tone her skin and unwinds by playing basketball or making ceramics, the benefits of which she first learnt at her Rudolf Steiner school growing up in Washington DC.Some days Im forcing myself to work out and its probably more important that I rest.Im trying to learn that more.

Shes also using social media in her own way.I certainly dont do it the way Im supposed to, she says of her dabbles with Instagram – including a recent video of her hacking off her hair backstage on a shoot, with the caption, We shouldnt be left unsupervised.

I get a lot of feedback that my face is too strong and I should keep my hair very normal.I tried to play the game for a while and it didnt work, its not me, she explains.I feel like the girls who resonate today are authentically themselves and we shouldnt all have the same long blonde locks.

Certainly, walking to the beat of her own drum comes naturally to van Seenus; and has meant shes been able to create some extraordinary fashion images over her two decades in the industry.Tie me up, hang me upside down, dunk me underwater, Im like, “yes”, is how she describes her favourite shoots.But jumping and smiling, especially in stilettos, is the most challenging for me!Im like “Arggh, how do I do it?”

Photographs by Bibi Cornejo Borthwick.Styling by Verity Parker.Hair:Marki Shkreli at Bryant Artists.Make-up:Allie Smith at Bridge Artists.Model:Guinevere van Seenus at Next Management.Fashion assistants:Jesper Gudbergsen and Emma Simmonds.Photographers assistant:Alexandre Hertoghe.Production:Jessica Levy.Casting:Katie Lowe.With thanks to the Greenwich Hotel, New York (thegreenwichhotel.com)