A doctor who treated victims after the 7 July attacks and is a volunteer at the Olympic Games has said the "cathartic" opening ceremony has given him closure on the Tube and bus bombs.
Intensive care consultant Andrew Hartle from St Mary's Hospital, Paddington, was on duty the day after London won the bid for the Games in 2005.
He had a chance meeting with Lord Coe on the Tube last week and thanked him for the success of the Games.
Seb Coe said it was a seismic moment.
Speaking at Olympic Park on Monday, the London 2012 chairman said: "It was a seismic moment and a seismic conversation to have had with a volunteer."
Mr Hartle, sitting alongside him, told how he was inspired to apply to help out at the Games after the Tube and bus attacks on the capital.
He said 7/7 was never going to be a "normal day" as London had just won the bid and in the hours before the bombing people at work were quite cynical about the expected impact on transport.
"The day turned into something totally different because of the terrorist attack on London," he said. "I was there, I did my job. It wasn't the job we'd planned to do that day, but we did it well.
"For most of the last 7 years, those two events, the awarding of the Games and the 7 July bombings have been inextricably linked for me.
He said of the Games' curtain-raiser 10 days ago: "I found the Opening Ceremony quite cathartic. It gave me closure. London now is known for something else, for hosting a fantastic Games.
"London has changed as well. People come up to you, Lord Coe comes up to you, on the Tube train.
"Being part of that has been an astonishing experience. People are friendly, people are talking, the Tubes are working, it's great.
Mr Hartle is part of the medical services boxing team, the "insurance policy nobody wants to use", he said.
"I am praying that for the next week I sit on my bottom watching the fantastic sport," he said.
Seb Coe praised the efforts of the 70,000 Olympic and Paralympic volunteers and talked about the way the country had come together to watch and be involved with the Games.
He said: "It's one massive, massive thank you to the people of this country, what we have witnessed over the last week.
"Would I say I was surprised? Probably not, but do I think it's probably one of the most extraordinary things I've seen in my lifetime? Then the answer is 'yes'. People in their millions have joined in.
"It's one of the most extraordinary things I have seen in my lifetime."