This is the third time that James Thomas, 54, has run the London Marathon - but this year is particularly special.
James lost his mother Pauline in November 2017 after she suffered a stroke.
He explained: “Mum died of a massive intracranial bleed (a type of stroke) in less than three hours.
“There was no way she could’ve been saved. I don’t want to see anyone suffer like this.”
Money raised will go to The Brain and Spine Foundation - who specialise in helping people who survive a stroke, a subarachnoid haemorrhage, or suffer a spinal tumour.
An ex-England rugby player is also supporting the runners.
Non-running captain Brian Moore is lending a hand in terms of fundraising, by supplying signed merchandise such as rugby balls and shirts.
The high-profile fundraising team has been boosted by the likes of boxing journalist Gareth Jones and The Daily Telegraph.
So far, James has raised £1,300 - including Gift Aid contributions.
To donate, visit https://uk.virginmoneygiving.com/SomeoneSpecial/PaulineThomas1