'We wish to express our deepest sympathies to the family and friends of Claire Squires, who lost her life so tragically whilst running the London Marathon on Sunday.
'Claire donated the proceeds of her 2010 London Marathon run to The Children's Society, raising almost £2000 for some of the country's most vulnerable children.
'She also raised £640 for the charity in 2008 by completing the Great North Run.
'Contributions like Claire's make an enormous difference to charities like ours and we wish to pay tribute to her generosity and determination to help others. Our hearts go out to everybody who knew her.'