Lee Jeffries leads a double life – as a full-time accountant near Manchester, and in his free time as an impassioned photographer of the homeless all over the world.

A self-taught photographer who started out taking pictures of stock in a bike shop, his epiphany came in April 2008 when, on the eve of running the London Marathon, he snatched a long-lens image of a homeless girl huddling in a doorway, and felt compelled to apologise to her when she called him out for it. Their resulting conversation changed not only his approach to photography; it changed his life.

Since that day Lee has been on a mission to raise awareness of – and funds for – the homeless. His work features street people from the UK, Europe and the US whom he gets to know by living rough with them, the relationship between them enabling him to capture a searing intimacy and authenticity in his portraits. He has published two critically acclaimed fund-raising books, Lost Angels and Homeless, worked with the Salvation Army on a major campaign, and donated the half-dozen cameras he's won in prestigious imaging competitions to charity. He estimates he's given thousands of pounds of his own money to help those he photographs. All this, and he's still 'an amateur'.
We spoke to him on the eve of his new exhibition, Synergy, to find out more about what drives his crusade and how – and why – he captures his compelling images with the Nikon D810 and a single wide-angle lens.

How would you describe your imagery?

I use light and shadow in a religious way – my images have been described as 'religious iconography', and it's not an accident. A few years ago I went to Rome to get a rosary blessed at the Vatican for a friend's dying mother; she's now buried with it. It was probably the first entirely selfless act of my life and something I was driven to do. That experience had a huge effect on the way I viewed people, images, photography. I took pieces of that experience, and it informs everything I've become, both artistically and as a man. I began to view and feel love on a completely different level and that, ultimately, led to extended periods of loneliness. I go out onto the streets to seek refuge from it. When I meet homeless people, they're as lonely as me. I can recognise loneliness in somebody's eyes, and that drives me.

There are a lot of people doing what I do. In my opinion, they often focus on the 'look' rather than developing the process to tell a story. My images are driven by authenticity, by a genuine connection with the person and their emotions. I like to say I'm photographing from the inside out rather than outside in.

How did you get into photography?

When I was a kid my uncle had an accountancy firm and I wanted his lifestyle – the house, the car, the holidays – so I did a degree in accountancy and didn't do anything remotely creative until I was 35. By that point I had a cycling business and needed to take shots of the bikes – that's probably the main reason I picked up a camera. I'd never done any photography before, but something must have switched inside my head.

So what changed your focus to images of the homeless?

It was 2008 and I was in London to run the marathon. The day before, I decided to have a go at street photography with a 70-200mm lens, and I photographed a girl huddled in a sleeping bag in a doorway in St Martin's Lane. Then she saw me. She started shouting. Everyone was looking and I was totally embarrassed. It was a case of either getting away quickly or going over to talk to her. So I went over, sat down and started to talk. She'd been kicked out by her parents; she was only 18.

I decided at that point if I was going to be a photographer, it wasn't going to be typical street stuff. It was going to be something more intimate; more about meeting people and understanding them, stopping to talk and helping out where I could. Everything has been built from that experience. I had no idea how big it would get. I was just putting stuff on Flickr looking for comments. It's not something that I've driven – it's just happened. Love happens in weird ways, not when you're looking for it; and for me it's been the same with the photography.

Who has inspired you?

One of my biggest photographic influences is from history lessons at school, seeing haunting black and white pictures of WW1 soldiers. I'll never forget the emotion in their eyes. That depth of emotion and power is what I capture in my photographs, it's what hits you subconsciously and compels you to have a second look. It's speaking to basic human needs.

And there are the usual suspects – Don McCullin, James Nachtwey, Josef Koudelka – but I look at their message rather than their technique. But the people I meet – they're my biggest inspiration.

Why did you make the switch to Nikon?

It stems from eight or nine years ago, when I'd started looking at other people's stuff and joined a Flickr group. Flickr was very sociable back then, the place to be. Kirsty Mitchell [Nikon Fine Art Ambassador 2013-5] was a member, and eventually it was Kirsty who persuaded me to swap to Nikon.

It was an issue of resolution. I was asked to do a shoot with Gin Wigmore, a singer-songwriter from New Zealand who now lives in LA. She'd seen my homeless pictures and wanted something similar, but huge in scale, and my then system just didn't have the resolution. The galleries had been saying the same thing. And then, when I was doing my book, Lost Angels, I was told the resolution wasn't really good enough; we were on the borderline with what we could put into it.

So it had been at the back of my mind to update for a while, but I was reluctant as my entire workflow was built around that system – it wasn't so much the cost of switching that worried me, but the process. I'd resisted upgrading for years as I was scared it would alter everything I did. It was fear of altering the aesthetic of what I was trying to produce. I was working on a 15-in laptop… And there was the time factor involved in setting everything up again – I'm a full-time accountant!

But I stepped out of my comfort zone, got the Nikon D810, bought a huge iMac, and everything fitted into place. These days I use just the D810 with the 24mm f/1.4 lens and a small handheld reflector. I don't need anything else; hanging cameras off both shoulders would make me too conspicuous.

What do you rate most about your Nikon kit?

I use the D810 for the absolute clarity I get. When I drill into the eyes in post-production now, there's such a huge difference – the resolution is stunning. My jaw sometimes drops. I use the basic settings, and always underexpose. There's no time for anything else.

The 24mm is a great lens. For a portrait, it gives you a little distortion, and because I'm so close, right in someone's face, it creates an unusual character, a roundness, so it appears less flat. I first started with an 85mm but I prefer the way the 24mm renders a portrait. And it lets me get closer; I don't have to stand back like you do with the 85mm. I'm so close I can talk to them, and it becomes a natural part of the process.

Is it conflicting to combine this incredible emotional photography with the day job?

To be good at what you do you have to be emotionally available, whether that's photography or accountancy. I'm happy to work full-time as an accountant to pay the bills because I don't want to and can't do that with my art. My photography is so fulfilling personally, the money isn't a motivation.

I do my photography in my holidays, physically going out of my comfort zone. It's what I have to do to get these images. I do get trouble sometimes, but everyone you meet is different; some are receptive to you being there and some aren't. When people look at me, they can see I'm not a pushover – and the fact that I'm respectful, courteous and honest is important. I'm not hanging my camera out of the car window, I'm right in there getting dirty with these guys, and that's why they accept me.

My heart is out on the streets. I'm always looking for that next opportunity to get back out there. But I have responsibilities and I have to switch between the two. There are two sides to me – the accountant, and the photographer. The whole process has made me be a lot more honest – my art demands honesty.

I'm very much project-based – I'll take myself off for a couple of weeks, get a car, drive around, then start walking around talking to people. In a weird way I fall in love with them – I become part of their lives and they become part of mine. The photographs are the final piece of the jigsaw, they're my way of saying goodbye. All my emotions are released in the final image, and I process my images in tears. If I'm not crying, then the image isn't right.

What have you learned from spending time on the streets?

Homelessness is a very complex issue. I sleep rough when I'm out there, and it gives you a freedom like you've never had in your normal life – you don't answer to anyone, there's no one on your back, no deadlines, you're just living. It's very addictive. But homeless people become vulnerable to drugs and alcohol. They're often there as a result of relationship breakdown or leaving the armed forces, and they're in pain, and there's access to drink and drugs to take the pain away.

Skid Row in LA is like nowhere else – hundreds of people in a six-block area living on the streets. Every morning at 6am the police go round with their sirens on, waking them up and moving them on. There are homeless centres there to help, but they facilitate the problem by attracting people from all over the US. I remember meeting this one street guy in New York when I was doing the marathon over there, and two years later I saw him in Skid Row. I can't see it ever ending. At Christmas it was worse than ever – sheer numbers I couldn't comprehend.

But I'm never happier than when I'm out on the streets. Back home I'm lonely. Taking these experiences from the street drives me to raise awareness, and the photographs do make a huge difference. They aren't documents of a person's life; they're documents of emotion and spirituality, and I don't underestimate their social impact. They're auctioned to raise money, and recently the Swedish Salvation Army's ad agency asked me to go over and do some shots. The main three images were used all over Sweden – it was a huge campaign. They reached as far as Los Angeles. The idea now is to take it to the next level and to do it for the Salvation Army in the US or France.

Tell us more about the new exhibition…

It opened on January 27th at the French Art Gallery in London. It's the second show I've had with a stencil artist called Jef Aérosol – the first was in Paris last March. I met him when he used one of my images in a stencil and rang to tell me, and we came up with the idea to do something together. The idea behind the show is that Jef tries to interpret the metaphysical attributes of my images. For example, with the portrait of the man who looks like Jesus, I'd shot him against the repeating patterns of a car park which looked like wings, alluding to him being an angel. So Jeff interpreted that, and did half his face with a full-on angel wing.

What advice would you give to someone starting out?

Don't focus too much on the process of an image; focus more on why you're doing it. Are you passionate about what you're photographing? If you're not, you'll get found out! Do what you think is right. Have personal integrity. Create your own niche and style. Don't try to imitate; if you do, you're doing it for the wrong reasons. My style has had a lot of criticism – you've got to have a thick skin. But it works for me and I don't care what other people think.

Lee's latest exhibition, Synergy, in conjunction with French street artist Jef Aérosol, is running at the French Art Studio in London from January 28 to February 25.

For more information visit www.instagram.com/lee_jeffries/