NERVOUS chatter and anticipation fills the courtyard of the British Museum, which from a distance could be mistaken for the most recent venue of X Factor auditions.

The array of mis-shapen laundry bags, cardboard boxes and bin liners that decorate the queue, along with a fleet of green garden umbrellas set up across the vast space are the first clues that this is something a little different.

Paul Clark, 31 and Emily Mott, 26 are probably not the type of people you would expect to find in this queue.

The surveyor and lawyer from north London, have taken the Thursday off work to bring a mirror to the London leg of the Antiques Roadshow.

“It was in my grandmother’s house when I was a little girl,” says Emily. “It’s beautiful, I love it but we have no idea where it comes from. We have tried to contact antiques dealers to find out, but no one has got back to us. It’s not just the value I’m interested in, we just know nothing about it.”

Like Emily and Paul, many in the queue want to find the story behind their object. Fiona Bruce, the current presenter of the show and a Belsize Park resident, thinks this may be a large part of the show’s long-running success.

“It doesn’t rely as a format on me, or on our experts, it actually relies on the public,” she says, in between waving to the crowd and saying hello to passers-by, “because the public are ever changing and because their stories are ever changing it doesn’t flag.

“Even if people get bored of me, they won’t ever get bored of the things that come along.”

Eric Knowles, who has been a valuation expert on the show for 30 years, agrees: “The most interesting thing about working on this programme is the unpredictability of what you are going to see.

“I have never ever got bored of working on the show. In all honesty we have to trawl through a lot of this and that, and you can abbreviate this and that to arrive at that one gem,” he says mischievously. “It is a bit like mining for a diamond, you have to sift your way through. But it’s worth it.”

Closer inspection into the curious baggage of the queue reveals some intriguing potential gems.

Nikki Wollheim, from Bounds Green has brought some Victorian greetings cards, which she bought in Camden Market for �10 “just because they were pretty, really”. All share in the unquestionable atmosphere of the film set, with hurried crews and camera equipment that would look more at home in a Hollywood studio.

The Antiques Roadshow is something of an institution in British life. Many have sat down on Sunday evening to watch hopefuls bring their treasures, found, bought or inherited for valuation.

In the 33 years the show has been running, it has become one of the most successful broadcasts on the BBC, regularly attracting more than 6.5million viewers. The experts here have seen around nine million objects and 20,000 objects have been valued on film in that time. The first �1million valuation happened in 2008, when a model of Anthony Gormley’s Angel of the North was brought to the show by a council worker from Gateshead.

As the day progresses, so does Paul and Emily’s mirror: into the exclusive category of film-worthy. Swept away at first sight into security by one of the experts, the mirror re-appears as the centrepiece of a film set, accompanied by the couple and surrounded by a crowd of eager viewers. Everyone’s ears are pricked ready to hear expert Paul Viney deliver his verdict. After a string of questions he delivers the news that everyone has been waiting for. “At auction I’d expect this to fetch around �4,000,” he says to a collective gasp that has become atrademark of the programme.

“It’s unbelievable, a huge amount of money,” says Emily. “My dad predicted �400 so it’s way more than that. I think my family will be shocked.”