At 58, headteacher Jim Wolger is two years from retirement. Most people his age would be winding down, but Mr Wolger has a few ambitions he’s yet to fulfil. Over the next couple of years he wants to oversee the building of new premises for his school, Bridge School for pupils with profound and multiple learning difficulties in Islington, north London, and raise pound;1.5 million to equip it to the standard he’d like.

One thing threatens Mr Wolger’s carefully timetabled countdown to retirement: his hamstring. He tore it at the start of this year’s London marathon and has been battling back to fitness ever since. Injury permitting, by the time you read this, he will be in New York, hoping to notch up another marathon on his way to the ultimate test of endurance: the six-day, 150-mile Marathon des Sables across the Sahara. Then, and only then, will he be able to retire happily.

“A long-distance runner and a headteacher need the same qualities: patience and endurance,” he says. “I’ve worked here for 15 years, and for much of that time we’ve been pushing for a new school. Now we are finally going to get one.

“When I asked the staff what they would like to see built, there were some fantastic ideas, but a lot of things we couldn’t afford. So I thought, why not raise the money ourselves?”

Jim’s sponsored runs are the centrepiece of the pound;1.5 million appeal, designed to raise the profile of the school so that major donors can be tempted to contribute. But why marathons?

“People understand the commitment that’s involved. You have to prepare for a marathon; you don’t just turn up and run,” he says. “Besides, I like pain. I’m a hard man - in the nicest possible way. And running has been in my blood for as long as I can remember.”

Back in the 1970s, before “commercial” marathons were invented, Jim used to get together with other enthusiasts to run 26 miles. Just for fun. “To be honest, when events like the London marathon started up I didn’t go near them. It seemed very gimmicky. All these people turning up in hippo costumes.”

However, he soon realised their potential for fundraising; a single race can bring in up to pound;10,000. His own school benefits, and he also runs for Get Kids Going, which provides specially built wheelchairs to allow young people to play sport, and Facing Africa, which helps victims of noma, an infection that attacks children’s faces.

It is causes such as these which got him to the finish line in London this April, despite his injury. “I see the determination the kids at our school need just to get through life. Running a marathon with an injured hamstring is nothing by comparison. They are my inspiration.”

Mr Wolger has run the New York race before - his daughter lives in the city - and he loves the place. “There’s an unbelievable atmosphere. Everyone who runs is a New Yorker for the day.”

Last time, anxious not to take too many days off work, he flew out, ran the marathon and flew straight back again. “Not a good idea. When you’ve got all that lactic acid in your legs, being crunched up on an aircraft for eight hours with no leg room is about the worst possible thing. It was agony.”

This time he has booked a four-day trip, and is planning to visit special schools in New York. His governors are more than happy to give him the time off. “Fundraising is part of the work of any headteacher,” he says. “It’s part of my commitment to my school, part of who I am. The governors see that.” And his staff? “They love what I’m doing.”

Quite what they will think when he takes on the Marathon des Sables, in March 2007, is another matter. It is the equivalent of six back-to-back marathons, with one leg an 85km (53 miles) daynight stage, in temperatures of up to 45C. Oh, and it’s across sand. Competitors carry all their own food and equipment, the one concession being that they are allowed to pick up water at the start of each day.

As part of his preparation, Mr Wolger is carrying a full-weight pack around the New York course and tackling a series of endurance races in the UK. He has even enlisted the help of a teacher at school who is also a member of the Territorial Army to teach him desert survival techniques. So how does all this fit into an already hectic workload?

Mr Wolger’s wife makes sure he eats healthily and doesn’t overdo the training. He puts in a good run on Sunday mornings, when he leaves the house at seven and doesn’t get back until lunchtime, and restricts his weekday exertions to short early morning pre-school runs (he’s in work at 6am most days).

Once the Marathon des Sables is over, Mrs Wolger can look forward to seeing a bit more of her husband. Bridge School is due to move into its new buildings at about the same time that Jim will be slogging away across the Sahara. “It will be the perfect time to call it quits. I’ll leave on a high. But I want to go out with a bit of a bang.”

The couple are planning to retire to New Zealand, and Mr Wolger will be packing his running shoes. “I couldn’t think of a life without running.

When I’m running I go deep inside myself. I can solve all the problems of the world.”