Mark Fordyce worked for Cantor Fitzgerald, the British financial company which lost hundreds of workers in the terrorist outrage. Every so often, he plays a video tape of happier days.

But as the images flicker across his television screen, he is always taken back to the terrible tragedy at the World Trade Centre.

He watches former colleagues giving speeches as he hands over his work in a major creative project - right outside the former landmarks.

Many of those colleagues, he says, are now dead. They are as much a part of his memory as the pictures of World Trade Centre One and Two.

Mark, who now lives in Holgate, York, worked for Espeed - part of Cantor Fitzgerald. As senior creative director for the company, he was a frequent visitor to floors 100 to 105.

"I knew a lot of people in the World Trade Centre. The plane went in on floor 101," Mark said. "I watched in complete disbelief.

"I have the video footage of the last time I was there. In my mind, it is still there. As it is on the screen. But it obviously isn't. It feels very strange.

"On the launch of the project, we thought it would be a good idea to send a camera crew to the World Trade Centre.

"You can see people in the room, and a girl making a speech. They are no longer here."

September 11 still dominates Mark's thoughts. He says he needs to go back to New York, but he doesn't know when.

He said: "I think about them constantly. I think about a few things, it is very surreal. I haven't been back to New York since. I need to go back."