Tim Coulson, like so many others on 7 July 2005, did not realise how dramatically his life was about to change when he boarded the Tube.
An art and design teacher, Tim had by perfect chance boarded a train which would pass the one in which radical Islamist Mohammed Siddique Khan set off a rucksack full of explosives.
Today, he read the names of the victims at the tenth anniversary memorial service in Hyde Park.
"I consider it a huge honour to be able to read the names of all those people in a very public place, here in Hyde Park," he told ITV News. "Because it is important."
Coulson, an infrequent visitor to London who hadn't realised that the Underground was always so packed with commuters at 8:30 in the morning, still vividly remembers what happened that day.
He was caught up in a coordinated series of bombings which rocked the capital that day, killing 52 innocent civilians and the four Islamist terrorists who set them off, and injuring 700 more.
The blasts went off in three tunnels near the Aldgate, Edgware Road and Russell Square stations within 50 seconds of each other from about 8:49am. These were followed by another explosion which ripped a double decker bus in two in Tavistock Square an hour later.
Coulson was at Edgware Road, where six people died. One, 52-year-old Michael "Stan" Brewster, died in Coulson's arms.
Of the connections between survivors of the day, Tim says: "It's a wonderful bond that you build with these people. We all have a great love for one another."
He adds: "It's important to meet with each and every family that we can. That emotion that is shared, that understanding that we are still those people who took liberties with their loved ones to ensure that they were absolutely fine."
Within a minute or so of boarding, Coulson's eastbound train passed the one on which the bomber, Khan, was riding west. He remembers an enormous boom and a bright light - the result of a powerful blast from a homemade organic peroxide device.
As the dust cleared and terrified passengers were plunged into darkness, not knowing the source of the explosion - whether it was a gas main, derailment or a terrorist attack - Tim was faced with a choice. Should he head to the surface with his fellow passengers, or stay behind to help the dying or injured?
In an act for which he would be remembered as one of the "angels of Edgware Road", he chose to stay behind and venture into the other train alongside two others: Canadian journalist Peter Zimonjic and graduate Susanna Pell.
Nothing could prepare them for the scenes they would find after they broke through using emergency picks.
With carnage and debris everywhere, Coulson encountered Brewster, a father-of-two with, he thought, his legs trapped in a crater.
In fact, they had been separated from his body. Coulson stayed with Stan until he died.
"There's no way anyone should die alone. And I wanted him to know that - I know that he knew that," he says.
Tim continues to comfort others involved, even 10 years on. He says: "It is extremely important to me and every one of those families who lost someone, because they see a link with their family member, and an opportunity to share and develop and move on in this world of ours."
He moved on and found others to help, including Alison Sayer, an Australian who had been badly injured. He stayed with her for an hour before rescue came, and she credits him with saving her life. The two are now close friends.
Tim was forced to take early retirement on medical grounds, unable to continue the teaching job he had previously loved. Ten years on, he's a lot better, able to travel on public transport - including the Tube - but he will never forget what he saw.
"It won't ever disappear. If I close my eyes I can bring it back", he says. "It's one of those dense points of pain, really."