How the ‘Hardest Geezer’ ran across Africa and into an unlikely feud

Cook, for his part, acknowledged the row without necessarily getting involved. “There’s plenty of people before me who have done big runs and kudos to all of them because they are all huge challenges, so nothing but respect,” he said. Olsen wrote that “luckily this approach is very rare in ultrarunning, where sportsmanship is an important part of our little sport”.

In some ways, despite never having met and never having raced, Cook and Olsen follow a rich tradition of sporting rivalries, in the tracks of James Hunt and Niki Lauda, or Andre Agassi and Pete Sampras. It is the character vs the machine. The maverick vs the master. The self-promoter vs the self-effacing.

Olsen began running in Denmark, aged 12, with his father. “In winter we would be able to run across frozen lakes, leaving our trail in the fresh, untouched snow of early morning,” he wrote in his book, The Runners Guide to the Planet. He loved slowly getting better. “Running is possibly the only sport that requires the most patience; the most investment from the athlete. No victory, no step forward or improvement comes easily. Each step has to be earned in distance training.”

He discovered he was very good at it, so joined a club, then found he could run further than men three times his age. At 15, he ran his first marathon, setting off from the castle of Elsinore, famous as the setting of Hamlet. He ran it in three hours and 26 minutes. “During the next decade I achieved 31 minutes for the 10K, 1.08 hours for the half marathon, and 2.27 hours for the full marathon. Respectable times, yes, but not remarkable in the running universe.”

Olsen has a master’s degree in political science and has said he enjoys “everything from nuclear physics and French philosophy to computer games and long walks along the beach”. As he grew up, he began to question why marathons have to be the limit of running, so pushed things further, and further, and further.

Cook, by contrast, was a non-athlete at the same age Olsen was running marathons, and a self-confessed “fat lad with booze and gambling issues”. His childhood was troubled, his youth unmarked by achievement, so one night in his early 20s, feeling a “mess of a bloke”, he decided to do something about it.