A former attorney-general said that he still remembers the smell of debris from the day that the Twin Towers collapsed.

Mark Pettingill, a lawyer of more than 30 years, added: “It was acrid, obviously, just like with any type of smut, fire and dust.

“The city was full of that for some time.”

Mr Pettingill had visited New York City on September 10, 2001 to visit friends for two days.

He spent the morning of September 11 walking through Lower Manhattan to a breakfast meeting, even contemplating having dinner at a restaurant in the World Trade Centre.

It was not until he turned a corner, Mr Pettingill said, that he saw “smoke in the distance” coming from the northern tower.

“I remember thinking for some reason ‘oh, that’s a helicopter or a light plane that hit there’,” he said.

It was not long before dozens of people watched newscasts of the incident on a nearby television and heard people “crying out”.

Mr Pettingill said: “While they had the TV on looking at whatever this was and the news media questioning about it, that other plane hit.

“I heard that cry out in unison. I remember turning around, not looking at the towers but looking at the TV, and then you could see this massive explosion.

“I remember standing up and right away saying ‘this is a terrorist attack’.”

From that point on, Mr Pettingill said, New York City was in a surreal state of shock.

“It was like Day of the Dead with the zombies walking up the street,” he recalled.

“There was silence. People would stop and look when they weren’t walking. There was a palpable kind of air of panic and horror.”

By 10am, the southern tower collapsed.

Mr Pettingill said the tower “swayed like a drunken sailor” before it fell “like a house of cards”.

He added: “You couldn’t quite comprehend that this was going to fall down.

“It was such an iconic, magnificent structure — one of the tallest buildings in the world — something so significant about New York that nobody was thinking ‘that’s going to come down’.”

“I remember very distinctly thinking, it’s going to look really weird with just one of those towers there, this lost twin.”

Before long, however, the northern tower came down too.

Throughout the day, Mr Pettingill said, he heard horror stories from people he met.

One man he saw that afternoon could not stop staring at what became known as Ground Zero from his office window, because his girlfriend was an airline stewardess.

Mr Pettingill later found out that the woman was on one of the flights that crashed into the towers.

That evening in a bar, he added, he saw a young firefighter still in his kit and covered in ash.

The bartender later explained that the man’s entire fire station unit responded to the attack and he was instructed to stay by the truck.

It was reported that the team later got caught in the collapsing towers and the young firefighter, who sheltered under the truck, was the only one among them who lived.

Mr Pettingill credited the friends he stayed with – two professional forensic analysts – for keeping him calm and helping him to learn more about the attack.

He stayed in New York for another week but did not get on a plane back home to Bermuda until a week later.

Mr Pettingill said that, since then, he had taken off every September 11 to reflect and pray.

He said: “I think I’ve come to realise it’s about the love of family in your life and how it can change so quickly.

“It had a direct impact on me, particularly over the years, about just the families that were lost that day, broken hearts and the people who never got home.

“I think out of that, one tends to have a realisation that life is fleeting.”