David collapsed with heat stroke just before the 25-mile marker of the London Marathon in October 2021, and had to be retrieved from the course and treated by volunteers from St John Ambulance.

Now the 36-year-old is gearing up to complete the London Marathon on Sunday 23 April to raise money for St John Ambulance.

David says: "I used to watch the London Marathon every year as a child and it was the only marathon I ever had any desire to do so it was a dream come true when I got a place in 2021.

"But my dream turned into a nightmare so close to the end. I don't remember much after mile 23 but I will always be so grateful to the runners who I've been told stayed with me until help arrived, and to the St John Ambulance volunteers who treated me.

"As much as I'll be running the London Marathon to finally cross it off my bucket list, I am so glad that I'll be running for St John Ambulance. To me, it is the perfect way to say thank you to the charity and their volunteers who will line the route on April 23 and save others just like they did for me."

He added: "Running a marathon can be a gruelling experience both physically and mentally, and I feel it will be tough emotionally as I get close to where I'd collapsed just 18-months before. But I am determined to make it to the finish line and to finally soak up the atmosphere on The Mall and get my hands on a London Marathon medal."

Following his collapse at 2021's London Marathon, David dusted himself down and went onto run marathons in Brighton and Vienna in April 2022, and also in Atlanta in March this year.

He also completed the 435-mile Lap of Anglia in August last year to raise money for the East Anglia Air Ambulance and celebrated a half marathon personal best at the Great North Run in September last year.

He also completed a 2,280-mile virtual challenge last year to run the length of the USA's famous Route 66. It took David 363 days to cover the distance from Chicago on the east coast to Santa Monica in California along the west coast.

The Route 66 challenge came after David completed a similar challenge in 2021 to run the equivalent distance of Land's End to John O'Groats which ended when he crossed the finish line of the Grand East Anglia Run in August 2021.

You can support David’s fundraising drive for St John Ambulance by sponsoring him via justgiving.com/davidblackmore86