“I won’t shed a tear if he beats me. The truth is he probably will.” So says Ben McCormack, a barrister with Garden Court North Chambers in Manchester, of his running partner’s prospects in this Sunday’s London Marathon.

McCormack adds, though, that by nature he is “more magnanimous” than his partner, and then reveals the reason for this generosity of spirit: he is running the marathon with his brother Dan.

“He’s a lawyer, too,” reveals Ben, 33, a solicitor turned barrister. “We’ve both been runners since childhood. I have to admit that he has the edge on me. But as his older brother, I like to let him win.”

Sibling rivalry is not what has prompted the lawyerly duo to enter the gruelling 26-mile slog through the streets of London. Instead, it was a book written by a journalist. “We both read Richard Askwith’s Feet in the Clouds, about fell running, and thought it was brilliant,” Ben says. “It’s one of those books that transcends the sports genre. It contains an account of running what’s known as the Bob Graham Round. We decided we had to do this, but that we needed a couple of years to get in shape for it. The marathon is part of the training process.”

If running the London Marathon as part of a training regime sounds a little extreme, spare a thought for anyone who takes on the Bob Graham Round. This is a fell race held in the Lake District where the challenge is to run up and down 42 peaks — in 24 hours. The race starts at Keswick and covers 72 miles. The man who gave the race its name first ran it in 1932 when he decided to complete the circuit wearing no more than a pyjama top and a pair of plimsolls.

Askwith, in his book, narrates the tale of his own attempt at the Bob Graham Round, having been lured into it by a fell-running friend. He experiences “the climactic ecstasy of settling down in an empty pub with a pint of bitter and a packet of crisps”, but makes no bones about the “greatest of all the joys of fell running: the fact that, every now and then, it is over”. Make no mistake: this is a bloody, stomach-churning enterprise that should be undertaken only by the super-fit.

The McCormack brothers are not far from being in this category. Both run to work, Ben to his chambers in Manchester (where he practises social welfare law), Dan to the offices of Collyer Bristow in London. Both have been runners since childhood, and both are aiming for sub-three hour times in this Sunday’s race. Ben says that completing the marathon will be “a small step in the right direction for the Bob Graham Round”.

Even allowing for the McCormack brothers’ higher than average standard of fitness, marathon running entails plenty by way of pain and suffering. What on earth is the appeal of long-distance running, whether up and down the hills of the Lake District or over mile upon mile of tarmac?

“For me, running is thinking time,” Ben explains. “It’s just about the only time in my life when I’m alone. There are no distractions and I can think about the world. I’ve always done a lot of running and I don’t get the whole ‘running with a Walkman’ thing. It’s about time and space to be alone with your thoughts.”

He allows, though, that running for 26 miles on one’s own can be “a lonely experience. That’s why I’m glad I’m doing the race with Dan. The trouble is that he is in slightly — just slightly — better shape than me. I might find that he disappears into the distance after a while.”

It is then that the elder brother’s privileges will come into play. “I don’t mind beating Dan but being older than him means that I like to let him come first every now and then,” Ben says. His wry runner’s humour is also evident when he reveals how he ensures that his work papers turn up in the office of a morning. “Running to work could cause a problem but fortunately one of my fellow barristers lives next to me. It’s thanks to him that I squeeze in a training run — and that my papers arrive in the office.”

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