Andrew Wilkinson, a worker at Weetabix, ran a personal best of 3:31:09 at the race in April.
Mr Wilkinson agreed to run for the Kick The Stick campaign for colleague John Sludden’s old school friend, Dick Mullen, who is trying to raise £40,000 for stem cell replacement therapy to treat his multiple sclerosis.
Mr Mullen was born and raised in Corby before moving to Milton Keynes.
Mr Sludden said: “Andrew not only ran the London Marathon on our behalf, but he also raised a massive chunk of money towards our fantastic total.
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“A personal best time of 3:31:09 was also achieved which deservedly earned him the club member of the month award from the Desborough & Rothwell Running Club.
“This enabled us to achieve a grand total of £1,155.
“A huge thanks go to Weetabix factories Corby 1 and Corby 2 for their donations.
“Also to my sister, Liz Ogilvie, and RS Components for contributing, plus friends too.
“The fund now stands at over £26,000 which has been raised in just 18 months.”