A doctor who treated victims of the 7/7 terrorist attacks said volunteering at the Olympics had given him closure on the tragic event seven years later.
Dr Andrew Hartle, an intensive care consultant at St Mary's Hospital in Paddington, said the attacks - in which 52 died and hundreds more were injured - had always been inextricably linked to the London 2012 games.
The terror attacks unfolded just 24 hours after the city celebrated being awarded the Olympics.
Dr Hartle, one of 70,000 Games Makers volunteering in London, said: "We had just won the Games and the only thing people were talking about during the first hour of work that day was the Olympics. Most of us were pretty cynical. What was the impact going to be on those who lived and worked in London?"
He added: "Then, as you all know, the day turned out to be about something completely different, with the terrorist attack on London. I was there and I did my job. It wasn't the job we planned to do that day, but we did it, and we did it well.
"For most of the last seven years those two events - the award of the Games and the July bombings - have been pretty inextricably linked.
"I found the opening ceremony really quite cathartic. It really gave me closure. London is now known for something else - it is known for hosting the Games. Being part of it has been an astonishing experience."
Dr Hartle, who is part of emergency medical services at London 2012, said he hoped his skills would not need to be put to use: "I am the insurance policy no-one wants to use."
London 2012 chairman Sebastian Coe described hearing Dr Hartle's story as a "seismic moment". The pair met by chance on the Tube last week, and Dr Hartle thanked him for the opportunity to volunteer.
Commenting on the meeting, Lord Coe said: "That really summed up to me what the volunteers are doing here and that is a conversation I will remember for the rest of my life. That was a seismic moment in terms of conversations I've had with volunteers."