A devastated mum is combing through pictures on the internet and appealing on social media to find evidence that proves her son didn’t cheat in the London Marathon.

Elizabeth Lee, 36, from Poplar, needs to find a picture of her son Ryan Lee running the marathon in Greenwich or Charlton.

He wasn’t picked up by the tracking system passing the 5km mark, meaning he has effectively been disqualified from his first marathon.

She told News Shopper: “Unless we can prove he ran and didn't cheat he will have to return his medal and be blacklisted for all future events.

“He is only 18 and is devastated.

“At the very beginning he was wearing a blue Adidas jumper and then he took it off and carried it in his hands until the Cutty Sark.

“He was wearing a yellow Dogs Trust T-shirt and his number was 4728.”

Ms Lee has been posting on social media to try to reach as many people as possible who could have taken marathon pictures with her son in the background around the 5km mark.

She’s also been sifting through thousands of official photos online to try to catch a glimpse of her son and get him officially vindicated.

Marathon organisers have already removed him from the list of finishers on the site.

Ms Lee says: “So he's effectively already been disqualified.

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“We are gutted for him to be going through this – he is 18 and was celebrating a massive achievement of finishing the marathon and was so pleased with his time of three hours and 58 minutes.

“To be accused of cheating has upset him so much.

“We are determined to prove that he isn’t a cheater!”

Did you take any pictures in Greenwich or Charlton showing Ryan Lee at the five-kilometre mark of the London Marathon? Email helen.corbett@london.newsquest.co.uk.