Carl Fitter, of All Saints primary school in Wouldham, takes some of his pupils for weekly swimming lessons at Strood Leisure Centre.

Afterwards, when they have got back on the coach, he races back along the five mile (8km) route to the school on foot.

Mr Fitter said the coach spurred him on to go faster even though he had only beaten it a couple of times.

"Roadworks helped on one occasion before Christmas, when the bus had to make a detour," he said.

"If I get to the gate before any of the children do, then I've won."

Mr Fitter is hoping to raise more than �1,000 for the Whizz-Kidz charity when he runs in the marathon on 23 April.