A city banker who collapsed from heat exhaustion at this year's London Marathon has decided to run again in aid of medics who treated him. 

Sam McCarthy, 31, of South Woodford, pulled out of the 26-mile Virgin race near the finishing line after falling ill. 

He was treated by St John's Ambulance (SJA) at one of the last checkpoints on the route.     

Describing the incident, Mr McCarthy said: "I was disorientated and struggling. The St John Ambulance volunteers were incredible. 

"They were patient, helpful and compassionate. They got me back on my feet and feeling OK, although my pride was a little dented.

"It was then that I noticed how many other people they were helping and this was at just one of the many medical stations along the route. 

"That’s why I want to run again - to try and give something back to those who helped me."

He is encouraging ballot place holders, otherwise known as 'fun runners', who do not have to be sponsored to join him in fundraising for the first aid charity. 

He added: "I can’t think of a better charity to fundraise for at the marathon because without the first aiders lining the route, thousands of runners would be forced to pull out because of injury or illness."

More than 1,000 SJA volunteers made up of aiders, doctors, nurses and paramedics line the route every year with approximately one volunteer for every 35 metres.