Of all the art fairs that hit London every October, one of my personal favourites has long been the Affordable Art Fair, which comes a week or so after the behemoth that is Frieze. I think it's the atmosphere that does it – AAF is actually fun! And as the name suggests, it's affordable, which means even severely impoverished arts editors can afford to buy a little something.

Ahead of this October's instalment I met up with Chris Guillochon, Director of one of Putney's only contemporary art galleries, called, aptly, Guillochon Gallery. I've actually known Chris for a good while now – he jacked in his lucrative career as a banker a couple of years ago in order to set up his own gallery and we've occasionally met up to discuss the art world and such like, as well as frequently bumping into each other at Private Views across town.

Standing in his temporary space in Putney Exchange – he also has a permanent gallery on Putney Bridge Road – it's clear that things are beginning to come together. In comparison to the shopping mall outside, where every shop window clamours desperately for the attention of passers-by – the Guillochon Gallery space is crisp and calm. Works by up-and-coming contemporary artists hang neatly on the white walls – I notice well-chosen pieces by the likes of Darren Coffield [pictured above], Lee Maelzer, Ethan Pollock and Alexander Heaton.

Chris really seems to have found his direction, and he agrees: “most of the works here are monochromatic, quite melancholic, fairly graphic, and mostly figurative.” There's a focus on 'traditional media', so primarily works on paper, painting, photography, printmakers, and a little bit of sculpture. “I like to see the graft of the artist,” he says, “as well as a strong degree of intellectual integrity”.

But what made him give up banking in the first place to dive into the strange world of contemporary art? After going through some difficult personal circumstances, Chris just had a re-think: “I was 35, working in the City, and completely burnt out, and I just wanted to go back and do something I enjoy. I did A-Level Art and History of Art and I'd always been a collector in my banking days. I decided I wanted to run an art gallery, but didn't really know how to go about it. I thought, 'well there are two ways to do it – either go and do an MA in contemporary art theory or something or just learn from the ground up.'

Sensibly, Chris opted for the latter. He did a stint at Monika Bobinska, during which time he went to Art Basel, helped on the exhibitions, met artists, curators and collectors – “I learnt the whole bit really” – and after advice from the likes of Patrick Heide, James Freeman at Sesame Gallery and Pippy Houldsworth, he set up on his own.

Since then, Chris has organised various projects – primarily in Putney and south west London – enlisted the help of external curators, and exhibited at Affordable Art Fair, Bristol. So the London edition of AAF seems like the logical next step? “Definitely. On the organisational side, I find the people at AAF outstanding. I've heard independently from a lot of people that they put a lot of the bigger art fairs to shame in terms of their PR, how they're organised, their courtesy and relationship with the exhibiting galleries. They're very loyal, and always very strong. I've found them fantastic.”

This October, Chris will be selling works by Darren Coffield, Ethan Pollock and Alexander Heaton at the fair, as well as a couple of printmakers. “The centrepiece,” he says, “will be one of Darren Coffield's Marilyn pieces – part of his 'Dead Famous' series of works on paper. At around £2,800 that'll be the centrepiece”.

Coffield, Chris tells me, is the only artist to be shortlisted for the BP National Portrait Prize, the Threadneedle Prize and the John Moores Painting Prize this year, so he expect his work to do well, but then, he admits, “predictions are always difficult. In my banking days, I had to sell financial products – I didn't believe in the products, the clients didn't want them, but I had to try and sell them. But art – it's a soft sell. People either like something or they don't. I'm here just to give them a little bit more information or tell them more about the artist, but essentially all this is work I believe in. I'll live and die by the sword – I won't change my direction for anyone, even if I'm not making any money.”

And it's more fun than banking? “Absolutely!”