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For Manchester King David deputy head boy Charles Burns, the marathon was the second element of a London sporting double.
Having taken in the all-Manchester FA Cup semi-final at Wembley with family and friends, the Prestwich teenager ran to raise £3,000 for the Children with Leukaemia charity.
"My biggest running achievement before this was winning the 1,500 metres at school, but that's nothing compared to a marathon," he said.
Charles reached the 22-mile mark in three hours, but took 90 minutes to cover the final four miles or so because of a knee problem - "an old football injury which had ironically set me off on my fitness regime two-and-a-half years ago. I had loads of energy left. I know that next year I could easily run a sub-three hour time."