Stories that define the bravery of London attack victims and responders 20 years on

Today marks 20 years since the 7/7 attacks, which saw four suicide bombers kill 52 people and injure 770 others on the London transport network.

The attacks on 7 July 2005 all happened within an hour of each other, with the bombers having met at Luton railway station in the morning before heading to King's Cross. Shezhad Tanweer detonated his device at Aldgate, Mohammed Sidique Khan at Edgware Road, and Germaine Lindsay between King's Cross and Russell Square - all within three minutes of 8.50am.

Habib Hussain detonated his bomb on board the number 30 bus at Tavistock Square at 9.47am. Two decades have passed, but for the victims' families, survivors and the responders, the impact is still being felt.

Sky News spoke to some of the people profoundly affected by the attacks. Passenger went back to the tracks to save lives Adrian Heili was in the third carriage of the westbound Circle Line train heading towards Paddington.

It was in the second carriage that Mohammad Sidique Khan blew up his device at Edgware Road, killing six people. If Adrian hadn't been there, it may well have been more.

He managed to get out of the train and, having previously served as a medic in the Armed Forces, instantly made it his mission to save as many lives as possible. "Instinct took over," he tells Sky News.

His bravery first brought him to Daniel Biddle, who had been blown out of the second carriage and was now trapped in a tight space between the tunnel wall and the track. Adrian remembers crawling in blood to reach Daniel, who he now calls Danny.

His left leg had been blown off, his right severed from the knee down and he lost an eye, along with suffering other extensive injuries. He pinched shut the artery in Daniel's thigh to stop the bleeding until paramedics got to him.

Daniel has written a book about his experiences, titled Back From The Dead, and has credited Adrian with saving his life. Adrian eventually helped first responders carry him out.

Then he went back into the tunnel several times over to assist with the evacuation of 12 other people. He pays tribute to the first responders at the scene, who he says were "amazing".

"Myself and another gentleman by the name of Lee Hunt were the last to actually leave Edgware Road," he adds. "And I remember sitting at the top of the platform on the stairs and just looking out after everyone had left." In his book, Daniel has been open about his struggles with PTSD after the attack.

Adrian says he has had a "very good support network" around him to help him deal with the aftermath, and adds that talking about it rather than "holding it in" has been vital. "It still plays an effect on myself, as it has with Danny," he says, who he has formed a close bond with.

He says PTSD triggers can be all around the survivors, from police and ambulance sirens to the smell of smoke from cooking. "But it's how we manage those triggers that define us," he says.

On the 20-year anniversary, he adds: "It's going to be an emotional time. But I think for me, it's going to be a time of reflection and to honour those that are not with us and those that were injured.

"They still have a voice. They have a voice with me and I'll remember it.

I'll remember that day and that, for me, is very important." 'Instinctively, I decided to see if there was something I could do to help' You may recognise Paul Dadge from the photograph below, where he's helping a 7/7 bombing victim after she sustained severe burns to her face. It went viral before the social media age, featuring on the front of national newspapers, and in others across the world.

The Londoner, who was 28 at the time, was on his way to an office in Hammersmith where he had just got a job. He passed Edgware Road, where he saw a commotion as people rushed out of the station, and an emergency responder go in.

He didn't yet know that one of the bombers had just set off the explosive in their backpack. "Instinctively, I decided to see if there was something I could do to help," he told Sky News.

Paul, who was a former firefighter, made an announcement to those standing outside the station, telling them to stick together if they had been affected by whatever had happened and to wait at a shop near the scene until they had spoken to a police officer. Many had black soot on their faces, he says, adding that he initially assumed it was due to a power surge.

Eventually the store was evacuated, so Paul went with the victims to a nearby hotel, and it was while doing so that photographers snapped the famous photos of him comforting the victim with a gauze mask, who had been badly burned. He started noting down the names and details of those who had been injured, along with the extent of their injuries, so that he could pass them onto the emergency services.

It was only three hours after the incident that Paul found out the injuries had been caused by an attack. His actions had him deemed a hero by the public.

Read more:How Prevent is tackling extremism 20 years onWhy is the govt's anti-terrorism programme controversial? "I know that after that bombing had occurred, everybody worked together as a team," he says. "I think it's a bit of a British thing, really, that when we're really in trouble, we're very, very good at working together to help each other." He says he is still in touch with people he met on that day, including the victim he was photographed with.

He also says the rest of his life has been "carved" by that day, and that he is now much more politically active and conscious of how emergency services respond to major incidents. He believes emergency services are "a lot more prepared than they were on 7th July.