YOUNG Mike was spending his birthday at school when his teacher wheeled a TV set into the classroom. The news channel was reporting on a piece of history that he felt his pupils should witness.

They saw the twin towers of the World Trade Centre collapse and Mike might have been forgiven for thinking his father, a New York fireman, was dead. "But, as kids reason things, he said, 'God wouldn't let me die on his birthday," recalls his father Billy O'Keefe.

Suddenly it dawned on the teacher. He asked his class whose father was a firefighter. Five or six hands were raised in the air, and he realised he'd made a terrible mistake in making the children watch the events of September 11. Billy himself says: "I tell my son it's the happiest day of my life because he was born and the saddest because I lost so many friends that day."

His story is among the moving testimonies in 9/11: A Firefighters' Story, a film by British documentary maker Paul Berriff - one of the first of many programmes on all channels to mark the anniversary of the September 11 attacks.

The BBC has a whole package of One Year On radio and TV programmes, as well as a website devoted to the subject. BBC1 will show the documentary 9/11, filmed inside and around the Twin Towers, on the evening of September 11.

Channel 4's output features a season of films exploring how events that day changed the world in which we live. ITV's programmes include a Tonight With Trevor McDonald Special, Let's Roll: The Story Of Flight 93, using interviews and reconstructions to tell how passengers confronted terrorists on the hijacked aircraft heading towards Washington on September 11. Berriff's film is not only one of the first anniversary programmes to reach the screen, but one of the simplest - and all the more effective and moving for that reason. Under nine chapter headings, he follows New York firefighters through the terrible ordeal and beyond.

The award-winning film-maker, whose career behind the camera began as a photographer for the Yorkshire Post and then on BBC news at Leeds, is no stranger to danger. He was one of the first people to reach Piper Alpha oil platform after it exploded, escaped death when a volcano erupted around him in Nicaragua, and joined explorer Sir Ranulph Fiennes on three expeditions.

He'd already made plans already to make a film about the city's firefighters when the terrorist attacks happened. He was shooting another documentary in New York that day and rushed to the World Trade Centre when the first plane hit the building.

He was filming when the first tower collapsed. Berriff ran for this life with hundreds of others, fleeing an avalanche of steel and concrete. He was injured, but recovered. Others around him weren't so lucky.

The actual event occupies very little of the hour-long documentary, which concentrates on the aftermath. With battalion commander Mike Puzziferri providing the commentary, this gets to the heart of how firefighters are coping.

Puzziferri and Berriff met up again at Ground Zero as the search for those who died continued amid the still red hot rubble. After 261 days, the site had been cleared and hopes of identifying every victim ended. Some 20,000 body parts were found and tested for DNA, but, of the 2,820 people lost in the Twin Towers, only 1,330 were identified.

Fireman Mike Lynch was one of the last to be found, and his father talks openly about his loss. His son's body was found intermingled with a female, signifying either he was protecting her or carrying her. "If he died that way, we are very grateful," says his father.

Every day a story in the press reignites the emotions of surviving firefighters. The past was forgotten for a while at the firehouse annual picnic, although the fact remains that 600 children now have no daddy and 300 wives no longer have a husband.

Those who survived are coming to terms in different ways. The wife of Bob, who was trapped in the stairwell of the north tower and one of the last to get out, is still concerned about him because he relates the story of the tower collapsing in such an unemotional, matter-of-fact way. "I don't think it's got through to him, or maybe this is his way of dealing with it," she says.

For assistant commissioner Steve Gregory just driving to work and seeing the altered Manhattan skyline is a reminder of that day he nearly died, the day that hundreds of his men did.

"They weren't the most beautiful buildings in the world but they sort of made a statement," he says. "You look over there and they've gone, and New York is still here. It seems a little different now, it's changed."

Years from now, other programmes will undoubtedly take a fresh look at September 11. Just as Diana's Funeral: Five Years On - also on C5 next week - does. This, however, is nowhere near as good as Berriff's film. The first 50 minutes is spent re-showing the funeral interspersed with talking heads, including Brian Sewell, Andrew Morton and Beatrix Campbell, commenting on Diana's life and times.

This tells us little we didn't already know. The "scoop" is a guided tour of the London apartment of Diana's lover Dodi Fayed, who died in the crash that killed the princess. The place has been kept as it was before his death, as a sort of shrine.

What does become apparent is that the British monarchy, whose handling of the Diana situation made it unpopular, has recovered from the criticism as demonstrated by the success of the Queen's golden jubilee celebrations. But it took Diana's death to shake up outdated royal attitudes.

Little did newspaper editor Piers Morgan realise when, on hearing of Diana's death, he declared this was going to be the biggest story of his lifetime that events on September 11 would prove him so wrong.

9/11: The Firefighters' Story (Thursday, C5, 8pm)

Diana's Funeral: Five Years On (Tuesday, C5, 8pm)