"I'm glad I have been able to come and pay my respects properly," said Prime Minister's wife Samantha Cameron on an emotional visit to Ground Zero.
Her husband David looked on as she laid flowers at the memorial site of British victim, Katherine Wolf – whose name is listed alongside others who perished in the tragedy.
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Swansea-born Katherine was working on the 97th floor of the World Trade Center's North Tower when tragedy struck.
On the sombre visit, the couple extended their support to Katherine's husband, Charles, who kissed the site where his wife is honoured as the couple stood beside him, their heads bowed in respect.
Completing the group was New York mayor Michael Bloomberg.
Samantha was on a business trip in Manhattan when the attack happened. At the time she was pregnant with their first child Ivan and David spent five frantic hours trying to contact her.
She said: "Memories of that day will stay with me forever".
"I just couldn't believe it had happened. And to see the aftermath and the effect on the city was just so shocking." She added. "I often think about the people who died and their families."
In TV interview afterwards, the British leader emphasised the importance of making the world a better, more secure place.
"Here at the site of the Twin Towers, Ground Zero, here is the place to remember why what we do overseas is so important, so people are safe at home."