He calls himself the Tree Hunter.
For 13 years, Rob McBride has been walking the Offa’s Dyke Path, a 177 mile trail that hugs the border of England and Wales.
It is a route that winds its way through thousands of years of history, and Rob has been searching every field and hilltop for reminders of our past.
“Some of the trees around Offa’s Dyke have watched the Romans march into Wales,” Rob explains.
“People and trees have been intrinsically linked together for hundreds and hundreds of years along the border.”
Armed with a camera, notebook and measuring tape, Rob has identified many of the country’s most historic trees - some are thousands of years old, towering oaks that stand on the site of bygone battlefields.
But for many others, time is running out.
“There are so many special trees just literally falling over, falling by the wayside and we’re losing them,” says Rob. “And sadly they don’t have legal protection. If you want these trees protected in law, we have to prove that they're worth protecting. Because when they’re gone, they’re gone for good.”
Rob shares his discoveries with the Woodland Trust, who are compiling an inventory of Britain's ancient trees. He doesn’t get paid to do it - instead, he sees it as important work that no-one had ever thought to do.
His Offa’s Dyke odyssey has led him to some timeless treasures, including a yew dating back to around 500 BC and a giant oak measuring 11 metres wide.
"It's like being a landscape detective," he explains.
Rob’s tree hunting adventure along the border began as a form of therapy during a difficult period in his life.
“I used to be a software engineer,” he explains. “And like many people in this twenty-first century, I was dealing with the pressures and strains of work: too many hours, not enough work-life balance.
"And I had a breakdown, a mental health breakdown. I was signed off sick for two years.
“My father was a football and fitness fanatic and I took a leaf out of his book. I realised I needed to get out and exercise. For me, sitting by a tree, especially in the greenery, was free medicine. It restored me.
“Trees saved my life. It’s not too big an exaggeration to say that. They were an enormous part of the recovery - an enormous part.”
Rob says that his fact-finding mission along the border is a way of “giving something back” to the ancient landscape that helped him to get back on his feet.
He finally completed the Offa’s Dyke Path last month.
It’s been an intensely personal journey, stepping into the sunlight after the darkness of the past
You can see more on this story in Wonders of the Border, tonight at 7:30pm on ITV Cymru Wales and watch it online after broadcast here.