The Dome Diner is packed with several hundred people in matching yellow jackets and hard hats, like the chorus of some futuristic show set on a building site. Could they, at any moment, leap into a hob-nail boot routine to the music of Peter Gabriel, the rhythm banged out with hammers, cutlery and pneumatic drills? Unfortunately not. These are some of the thousands of building workers rushing to get the Dome ready by December 31. But on the al fresco terrace outside (though still under the vast roof of the Dome), a few real performers are talking about their preparations for what is being called “the show of the century”. And Peter Gabriel really has written the music for that.

James Roberts, Paula Vacarey and Kirsty Apicella, aged 28, 24 and just-turned 18 respectively, represent something of the diversity of skills and experience of the young people from all over the country who have survived the rigorous auditions, interviews and months of training to be in the Millennium Show. As they chat, overlooking the expanse of zones and public areas - still a mass of cables and cranes - they are about halfway between the ground and a steel walkway under the roof from where they will be demonstrating both their aerial expertise and lack of vertigo.

The Dome has been described in terms of how many pints of lager (3.8 billion) or red London buses (18,000) could be crammed into it, as if the UK’s millennium celebrations might turn into a mad parody of a Japanese TV game show. But it does make an ordinary mortal quail to think of James, Kirsty and Paula, with 58 fellow performers, dangling from trapezes or bungee jumping from a height akin to that of Nelson’s Column. Thirteen Albert Halls (or two Wembley Stadia) could sit inside the Dome, so an arena at its centre will be curtained off with huge blue sails lowered from the roof for the shows. There will be seating for 5,000 and space for 7,000 standing spectators.

But enough of the superhuman statistics. Back to the people. James was one of 2,000 to answer an advertisement for the first wave of trainees a year ago and one of 600 auditioned at Circus Space, a circus training centre in London. Kirsty and Paula joined in the second wave in April this year. In each case, between 40 and 45 applicants aged 16 to 34 were chosen for the training which included dance, theatre and performance skills as well as rope-climbing, trapeze, bungee-jumping, stilt-walking and trampolining.

Julie Thornton, the course manager at Circus Space, says that trainees needed around two years’ physical training in gymnastics, circus or martial arts. She mentions one student, 19-year-old John Brady, as exemplifying the determination necessary to succeed. “He sustained a knee injury in the first group and came back, fit as a fiddle, to join the second. He’d left after Christmas and was in full training again at Easter.”

Julie is herself an aerialist with experience of working in contemporary circuses, the kind which depend on human skills and spectacular presentation rather than tricks with animals. Her students were taught by up to 50 trainers, which included visiting as well as regular instructors. The first batch of students, with James among them, has now completed the course and been awarded a Certificate of Higher Education, accredited by the Central School of Speech and Drama. The second group have had just four months of instruction.

So what was the training like? Anyone who has tried rope-climbing or trapeze knows all about calluses on the hands, aching limbs and skin raw from rope burns. And these brave souls committed themselves to long sessions, five days a week. Kirsty, who lives in Romford and joined the course almost straight from school, admits it was “tough - very tough. I come from a dancing background and it was very challenging for me.” There were moments early on when she even considered giving up. James breaks in:

“But, the presentation of the circus moves is done better by dancers.”

Kirsty also believes that mutual support was an important factor: “We helped each other to develop strength or creativity, whichever was needed.”

James, from Cardiff via Manchester, did street theatre and outreach work with a community-based circus in Rochdale. A stilt-walker, he admires trapeze and rope-work, which he describes as “aerial poetry” and hopes to add to his skills.

There is already talk, “a dream” says Paul Cockle, head of the Millennium Show, of keeping the company going beyond the year 2000. The word “legacy” crops up continually among the millennium celebration organisers. “What could be a better legacy,” he asks, “than providing work for the performers, who will have been seen by 12 million people, and to go on supporting training?” All 162 performers taking part in all the shows will have worked at heights simply not possible at most venues in the world. And they will have used specially developed equipment, some as yet unveiled, such as “rocketing bungee stilts” and “sail diver rigs”. There will be hundreds of costumes and a lighting rig that will be able to contend with the pearly gleam that, during most performances, will illuminate the roof from outside. The spectacle will be enhanced, Paul says, by the “actor-factor” - the talent, humour and daring brought to the show by strong-minded individuals.

Rehearsals began last month in the Dome itself. Until then the nearby Three Mills film studio space had allowed for training at about two-thirds the height of the public shows. Now, in the morning the Dome is a building site, in the afternoons the noise of drills and hammers is muted to allow rehearsal, and by evening it is a circus space. “It’s nice here, then”, say the aerialists. “Peaceful”.

The performance’s strong storyline tells of a family divided by conflict between the generations. Sophia, the wayward daughter, defies her family with her love for Skyboy, a mischievous dreamer. There will be two casts supported by understudies and “swings” - performers flexible enough to fill any role. There will be up to five performances a day, each lasting 28 minutes with an extra 20 minutes of pre-show entertainment.

Safety is, of course, paramount. Performers use safety lines and paramedics will be on hand at all times. Technical support teams train closely with the performers “at height” to minimise danger.

Of a technical crew numbering 160, 15 were recruited from a special 10-week summer school. One of these is 26-year-old Natashka Brown. A graduate of the London College of Fashion, she was formerly an events manager, staging fashion shows which featured dancers and magicians. She was one of 38 successful students among 50 young people from south east London who trained for the Foundation Award for Technical Production in Live Performance, newly validated by the Central School of Speech and Drama.

Natashka is delighted with her new qualification and well aware of the weight of responsibility on herself and the team to “keep the props safe and looking good”. Like the performers, the crews are expected to be flexible enough to cover for each other, on the ground or “at height”. Joanna Yates, who set up the summer school, said its aim was partly to challenge “the white male establishment” that dominates the technical and production aspects of the theatre world.

In the last fortnight of the course, the students became a “real” back-up crew for the performers’ demonstration show and they were, says Joanna, “fantastic”.

Her enthusiasm and that of her colleagues is deeply affecting - if half the buzz of excitement expressed by these young people communicates itself to their audience, there will be 12 million very cheerful people by the year 2001. And a “legacy” of newly qualified and frighteningly fit young people to take their place in 21st century Britain.

For Dome tickets, tel: 0870 606 2000. Web site: www.dome2000.co.uk