Tube driver Vaughan Thomas can recall with clarity the moment a Saturday morning journey on the network changed his life.

It was shortly after 9am on June 23 2007. Tony Blair was preparing to stand down as prime minister, Rihanna’s Umbrella was midway through a 10-week reign at the top of the singles charts, and anti-war activists were setting up an “illegal” camp in Westminster to protest about government policy in the Middle East.

Underground, a casually dressed young man made his way along the eastbound platform at a central London station and stepped purposefully on to the tracks.

CCTV images from the scene later showed headlights emerging quickly from the darkness just as the man did so. It was not enough time for Mr Thomas to stop his train.

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“I noticed a young man in casual clothes step out and was standing on the track looking at me,” Mr Thomas, a Welshman originally from Port Talbot, told the Press Association.

“As you can imagine, it was an awful shock to see something there that shouldn’t be there.

“It became clear he wasn’t going to get out of the way.

“So I closed my eyes.”

More than a decade later, 61-year-old Mr Thomas remembers the immediate aftermath – the ingrained necessity to make the train safe, alerting passengers that they “may not be able to get off for a while”, and dealing with a witness who tapped at his watch asking when they could get going again.

It was the first suicide Mr Thomas experienced first-hand during his eight years’ service with Transport for London (TfL). The next day, he was granted permission to sit in the front cab next to a driver and retrace his route, this time continuing fully into the station where it happened.

Each time I was coming to a station I was assessing if I had seen them here, could I have stopped?

He was given the all-clear to return to driving duties a month later. But the incident continued to play on Mr Thomas’s mind.

“Each time I was coming to a station I was assessing if I had seen them here, could I have stopped?” he said.

“For the next several weeks this was going through my mind.”

But it was only when a police officer spoke to Mr Thomas some time later that he truly accepted he did all he could to avoid the collision.

“They were able to show me pictures of the young man entering the station, going down the escalator by himself. Standing on the platform,” Mr Thomas added, his soft voice breaking slightly.

Mr Thomas was shown CCTV of the incident, proving there was nothing he could do to avoid the collision.

“At that point – I knew, it wasn’t my fault,” he said. “It was the first point I cried.”

He later learned the man had arrived in the UK from Europe but was convinced he had a serious illness. He got tested but could not bear the wait to discover his fate. He called his parents, wrote a note, and took himself off to the Tube station. Two days after his death, test results proved negative – the man was not ill.

“I still think about it occasionally,” said Mr Thomas, who is among the majority of Underground staff to have gone through a suicide prevention programme credited with a reduction in such incidents on the network since the end of 2017.

“When you hear about other people having similar incidents, of course it comes back. When people come back to work we often have a discussion about incidents to support one another.

“If I could go back in time and speak to that young man, I think I would ask him if he wanted to talk, because if he did I was ready to listen.”

– Samaritans is available 24/7 every single day of the year to listen and offer support to anyone who is struggling to cope. People can contact Samaritans by phone, free of charge, on: 116123, via email: jo@samaritans.org or visit www.samaritans.org to find details of their local branch.