A woman with a rare tissue condition completed the marathon in eight hours 18 minutes.
Lara Bloom from Bushey decided to enter after watching others pass the finish line last year while she was collecting for charity. As her condition prevented her from running, she decided to walk the 26 miles instead.
"I thought, how hard can it be to walk it?" said Ms Bloom, 30. She knew the challenge would be "pretty drastic" for someone with Ehlers-Danlos, a connective tissue disorder.
She had got around "on sheer determination - I think I broke a bone in my foot. But I had to get that medal. As most of the crowds had dispersed by the time I finished, I was so grateful for the 50 family and friends who cheered me on to the end. It was just incredible." She is well on the way to her £10,000 target.
Ms Bloom said she had at times regretted setting her self the challenge. "I underestimated how hard it would be. "I've gone through every kind of pain threshold imaginable. I was going against everything my body wanted." A few weeks before the marathon, she was hospitalised with a chest infection. Friends and family appealed to her to drop out but she was too stubborn to quit. "I decided I was still going to do it whether I finished or not. I always try not to let my health get in the way of living an ordinary life."