By Davina Fenton
On the day of the 7/7 bombings in 2005, Pc Richard Oakley was one of the first police officers to arrive at the scene at Russell Square station.
Twenty-six people were killed when a bomb was detonated on a packed Piccadilly Line train just after it pulled out of King's Cross station.
Pc Oakley, was just 21, and a relatively new member of the British Transport Police when he responded to the terror incident.
"We were met with carnage, " he told ITV News.
He also witnessed many people being brought up to the station's booking office with "severe burns, lacerations and missing limbs".
Recalling his memories of the day, Pc Oakley said: "You go into the mode that you're trained to deal with.
"I always remember quite a few people who were laying on the floor that were suffering burns injuries."
When Pc Oakley got back to the police station later that day, the officer said he "curled up in the corner of the locker room and cried".
"I think my body didn't know how to deal or process it," he added.
He then returned to work the next day "because you don't want to let people down, it's that 'man up' mentality".
But in the aftermath of the incident, Pc Oakley began to experience nightmares about people he had been unable to help.
He then reached his lowest point in December that same year when he had a nervous breakdown.
"I'd heard the slightest noise outside and I'd be up at the window...I was very, very jumpy."
"It all built up on top of me to the point I ended up locking myself in the bathroom and hiding away because I couldn't cope."
Pc Oakley went on to see a psychiatrist but found it did little to help. He then continued to struggled for a number of years.
In 2015, he was diagnosed with post-traumatic stress disorder (PTSD).
After years of suffering things finally changed for the better when Pc Oakley was treated by renowned hypnotist Paul McKenna at a conference
McKenna treated him with a pioneering technique called Havening which he practices on people who have experienced severe trauma.
"It completely reset my brain in how I approach and think things," he said
"That one session did it for me," Pc Oakley said, adding: "I don't have nightmares any more."
The 33-year-old now wants to help other people suffering with PTSD and urges anyone in a similar situation to seek help.
The officer has also started using social media get in contact other people suffering from the condition.
"It's ok to talk to talk about it. The more we encourage people to talk about mental illness the more we can help them," he stressed.