Adventurer Karl Bushby has been walking around the world for 28 years and now the end of his journey is in sight.

I have been writing about him for most of that time, but although we have spoken frequently and exchanged hundreds of emails we have never met.

We are in the village of Havré and I am joining Karl on a five-mile (8km) stretch to Mons. It is part of the final march to Calais, from where he plans to swim across the English Channel in October.

Dressed in shorts and a T-shirt which bears evidence of a roadside repair, Karl - sporting a grey beard - appears in the car park of a Belgian railway station.

He is pushing a trolley laden with camping equipment and other essentials.

Karl set off from Chile, heading back home to Hull, with two self-imposed rules: he cannot use transport to advance and he cannot return to the UK until the walk is complete.

Sweat is seeping through his T-shirt, forming wing-like patches over his shoulder blades.

The former paratrooper set off in November 1998, expecting his walk back to his childhood home, where his mother still lives, to take about 12 years.

Some 28 years on, he is still going, with visa restrictions, the 2008 financial crash which cost him sponsors, Covid-19 and geopolitics having slowed his progress.

The 57-year-old has covered more than 30,000 miles (more than 48,000km) and a swim across the English Channel now beckons after Channel Tunnel bosses vetoed his request for access to a service tunnel.

Karl ducks into a shop and comes out with a bottle of water, flinging it under a bungee cord attached to his trolley, which he had made in Nicaragua early in the adventure. The Beast, as he calls it, is his lifeline.

We maintain a fast pace. In 30C heat, I am finding it hard to keep up, with Karl showing no sign of fatigue, despite having trekked 10 miles before lunch.

We talk about how he crossed the frozen Bering Strait in 2006 with French adventurer Dimitri Kieffer and his 186-mile swim across the Caspian Sea.

Discussing his crossing of the Darién Gap, which links Colombia and Panama, Karl says: "You're having to push through a dense jungle.

"You've got these river systems and lots of swamps. Laid over the top of that you've got the fact that it's a warzone."

Faced with the threat of kidnap, Karl sought to look as though he was homeless.

"Homeless people are pretty much invisible, nobody pays attention to them, so that was our intent.

"I did not want to be the blond-haired, blue-eyed gringo with the latest North Face equipment.

"I dyed my hair and skin and reduced my clothing to tatters. I carried my stuff in sacks."

A woman peers out of a window and looks bemused at the sight of two men and a trolley.

Karl invites me to push The Beast for a short while. The black fabric tape covering the handle is worn and peeling.

With each passing mile, our conversation becomes more philosophical.

I ask him what the biggest lessons have been on the walk.

"Tenacity is emperor," he replies.

Karl struggles to weave The Beast past a row of parked cars. "These towns can be fun assault courses," he sighs.

Returning to the question, he adds: "Coming from a military background, you don't necessarily see the best in people, so it has really been an eye-opener.

"From day one, I have been received with open arms from the rest of the world."

Karl talks about the "kindness of strangers", noting how one family in Chile became "almost like a second family".

"They were driving out for eight hours at a time to find me and feed me on the side of the road," he recalls.

I reach into my rucksack and retrieve a letter from Karl's mother, Angela Bushby. Also in the bag are packets of his favourite sweets.

"Mother remembers," he laughs, selecting the caramel wafers.

The pair last met in 2015.

"You're still her little boy, aren't you?" I ask.

"Apparently so," says Karl. "A very happy little boy with all that chocolate."

In the letter, Angela asks if he really must swim the Channel. Both mother and son know the answer.

And then comes a line that speaks volumes.

"You used to think you were useless. Well, you have proven you're not," Angela has written.

I have always known Karl to be self-deprecating, but this leaps from the page.

He tells me he never felt as fit as his fellow comrades during his Army days.

Karl, whose father served in the SAS, says the Army helped build his confidence, but the "damage was done" in his early childhood, with undiagnosed dyslexia making him a target for bullies.

"I had no confidence," he says. "I was an underachiever. My dyslexia was not identified until my last year in school."

Karl, though, has never doubted he could finish his journey.

"There is definitely this sense of wanting to prove myself," he says. "To myself and others. We're talking about doing something other people couldn't even dream of doing."

For years, Karl has been relaxed about the end date. Not now. There is a real urgency.

"It's definitely time to call it a day," he says. "I don't want to keep this going for much longer."

"Oh my God, you are a legend," one excited young man tells Karl.

Does the future scare Karl?

"Yes," he admits. "One day I'm going to wake up in my mother's house – 57 years old with nothing but my stuff in a bag next to the bed."

We arrive at a cafe and Karl orders an orange juice.

I ask him what the hardest part of the journey has been, but instead of talking about blisters or fears about crime, he says: "It's the relationships. I've fallen in love twice, lost them, and that leaves marks.

"The physical pain stuff – yeah, that's all doable. In terms of falling in love and then having to just carry on the walk? You're going to lose it."

He tells me he gets a "real buzz from a good horizon".

It will surely not get much better than the first sight of the white cliffs of Dover.

As we stand in a beautiful square, the famous Belfry of Mons looming over us, I ask Karl if he ever pauses to truly soak up the sights.

"Sometimes you just don't have the energy," he admits.

"In a place like this, you'll take it in. You'd be surprised how many times I found myself in a place reminding myself I will never be here again."

I hope our paths will cross again... on English soil.