A grandad, 79, has gone viral on his granddaughter's TikTok after completing his 27th London Marathon.

Bob Smith, of Upminster, finished the event on Sunday (April 21) and the moment has been seen by more than 650,000 people after Amelia Pearson, 19, shared it to the social media platform.

The 79-year-old ran his first marathon in 1992 and has taken part in each consecutive event since 1999, fundraising for Sense, a charity that supports people with complex disabilities.

Ex-teacher Bob, who said it was one of the coldest races he could remember, ran this year's marathon in six-and-a-half hours.

@millmousee My grandad Bob Smith is my inspiration❤️ #londonmarathon2024 #londonmarathon #marathon #grandad @TCS London Marathon ♬ Evergreen - music <3

"The most important thing in the back of my mind when I’m running is the children and young people," Bob said.

“Remembering the dedication of the teachers of deafblind children I have met gives me the extra motivation to get finished."

RELATED NEWS: Defroand proud to complete marathon in memory of late aunt

Bob had visited children and young people Sense supports before the race, who played a crucial motivating factor.

This year marked the 20th time Bob had fundraised for Sense and despite turning 80 in 2025, he aims to do it again.

Caroline Buckland, head of events and fundraising at Sense, said: "Bob has inspired many other runners and provided advice and support on the marathon route.

“We can’t thank Bob enough for his continued support of Sense over 20 years."

Bob, described as a "hero" and "legend" in TikTok comments, asked why so many had seen the video.

"Why would half a million people want to watch a video of me?" Bob reportedly told Sense after hearing about its success.

But the 79-year-old added it was good that people could watch it and learn more about Sense's work, which supports people across the country.

Bob, who hopes one day to be the oldest man to run the London Marathon, was further praised by Ms Buckland.

"All the funds Bob has raised go towards our goal of making sure nobody is left out of life, no matter how complex their disabilities," Ms Buckland added.

You can learn more about the charity at www.sense.org.uk