“I think I’ve worked it out,” he says quickly, perched in the empty flat in Bristol he has just moved into with his boyfriend, Kyle.

“I was a corporate monkey before this, working 60-70 hours a week, thinking that you need the car, the house, the great job, the pension to be successful, but I wasn’t happy." Both Smith and Kyle gave up their jobs for this challenge; Kyle, who also gave up his PhD to help, managed the entire operation.

“I knew I was gay," Smith says, "but because I’d gone through school being bullied about it I felt it was wrong. I was told it was wrong.” The bullying began when he was 10, when his parents sent him to boarding school to avoid disrupting his schooling while his father, who was in the army, was stationed in Germany. An outgoing child, Smith soon turned in on himself. The bullying continued.

“It was conditioned into me, so even though later on in life I found out actually being gay isn’t wrong, I’d gone so far that I couldn’t come back from it. Once I finally got to grips with who I was, I figured out that the true me could start to come out.

“I was held back for so long in my life, doing things for other people, that the moment I found something I could do for myself, that I loved in my heart…” He stops and repeats the word love. “…I wasn’t going to let that go. I think that’s given me the focus and determination – even on mornings where I’ve woken up and gone, Oh my god I can’t be arsed to get out of bed, when the rain is beating down and I really don’t want to go outside, but because of what I get from running…” He doesn’t finish the sentence, but adds instead: “I’d hate not to be able to run every day.”

Running daily is one thing, but completing a marathon every day is an experience beyond the comprehension of almost everyone. Pressure and toughness, however, is in his blood, he says. “My brother was a professional rugby player. And I have two parents who were in the military. At the drop of a gun my dad used to go off to war. He’d say to my mum, ‘I can’t tell you where I’m going but I’ll be back in six months. And she’d say, ‘OK, fine.’ We’re quite matter-of-fact. I find it very easy to compartmentalise things, which I think is how I’ve managed to structure myself and create goals in this project.”

What does Smith think about while he’s running? For the first time, he looks stumped.

“Most of the time I think about nothing,” he says. So the real allure is that running helps him to stop thinking? “Yeah. When I first started running I used to call it ‘filing time’ – if I had a problem I would go out and run and the shaking of running kind of shook everything to place in my head and filed it away.”

What does he think now, though, about finally finishing the challenge?

“I’m shocked to hell,” he says, laughing, before changing tone. “I think deep down I always had a belief I could do it. There’s always those nagging things in your head going, Nobody’s ever done this so what makes me special? But there’s no room for that self-doubt; the moment it comes in you’ve got to push it straight back out again.”