I join the queue of visitors who are eager to discover how to clinch the golden ticket: an Australian visa. We take our seats and the game-show begins. On the stage, a smiling Australian migration lawyer talks up the prize of a one-way ticket to the land of surf, sun and beer. "Once you get a visa you can sit on the beach for the rest of your life. You don't need to work if you don't want to."
At Emigrate, points win prizes. Later in the day, at stalls dotted around the fair, there are talks on how to gain the differing number of points required for entry by Australia, New Zealand and Canada. Each country has its own list of desired skills and professions and the fair's walls are pasted with posters cataloguing each nation's sought-after occupations. Are you a bee-keeper? A civil servant? Welcome to New Zealand. Hairdresser? Last year Australia was desperate for you.
Now, after admitting large numbers of Chinese and Indian scissor-hands, hairdressers are no longer required. Qualification for permanent residence can be a lottery but there are some certainties. All countries allocate more points for youth, English-language fluency and education. And if you are an entrepreneur with thousands to invest in your new country, Australia, New Zealand and America all want you.
Myths about points swirl around the show. To demonstrate the abundant migration misinformation, the presenter, Ben Willis, a migration agent and lawyer, asks, Paul McKenna-style, for a guinea pig who believes he or she has the 120 points to qualify for permanent Australian residency.
The victim says confidently that he is an engineer, aware Australia is desperate for them. "Do you have a BSc in engineering?" the presenter asks. "No. I switched careers later and took an MSc in engineering," he replies. It is not enough. The BSc would have given him the necessary points but the MSc counts for less.
The volunteer's face falls. The presenter looks vindicated: "My main message is: don't assume you will manage to get 120 points," he says.
Registering the wavering mood in the audience, he attempts to gee them up: "It's worth going through the hurdles or else you'll be stuck on the M1 thinking, 'what am I doing here?' Australia is the best place to be. Once you've made a decision to come, just do it."
To keep wannabe migrants' eyes fixed on the prize, we are introduced by video link-ups to Brits who have leapt through the migration hoops to settle in new countries. At one talk, entitled "Chat with Brits in Canada", we're presented to Maxine, a migratory role model who moved from London to Ontario two years ago: "She got a whopping 79 points! She only needed 67 to qualify!". Canada's craving for her postgraduate social work qualifications ratcheted up her score.
It's a gold rush for the emigration industry. The Office for National Statistics' figures show more British citizens left the UK in 2006 - 207,000 - than in any year since records began in 1991: 49,000 for new lives in Australia, 71,000 upped sticks for EU countries, mainly Spain and France, and 16,000 to the US.
More and more people hanker to move abroad. A 2006 BBC survey found that 13 per cent of 1,000 people asked were planning to emigrate in the near future, twice the number who wanted to leave when the same question was asked three years before.
Yet the British press and politicians have been so mesmerised by the rising number of non-British nationals arriving - which the ONS recently showed had swelled to 510,000 immigrants in 2006, double the number a decade ago - that the British exodus has been ignored.
Of course, emigrating Brits are nothing new. At the height of its imperial power in the 19th century, Britain experienced mass migration not only to colonies and dominions such as India, Australia, New Zealand, Canada and South Africa but also to countries with colonial connections, such as the US.
Professor Tim Hatton, a labour market economist from Essex University, estimates the annual emigration rate in the years before the first world war at around 5.3 UK citizens out of every 1,000, though this included a disproportionately high share of Irish emigrants when Ireland was part of the UK.
Even today, according to Jim Hammerton, emeritus professor at Melbourne's La Trobe University, who has written extensively on the history of migration, Brits are cashing in on the "colonial dividend", empire having established "common language and family ties to countries".
A couple at the Emigrate fair support Professor Hammerton's observation. The woman, in her late 30s, pacifying her toddler with an apple, tells me her parents came to Britain from India in the 1960s, and her husband had lived in Australia as a child for 10 years before they met: "I know it's possible to uproot a family and be happy."
Brits are departing their home country in greater numbers than the French or Americans.
The Institute for Public Policy Research estimated that 5.5m British nationals, or just over 9 per cent of the UK population, were living overseas permanently in 2006. It dwarfs the number of French living overseas, which is only about 1.2m, according to the Organisation for Economic Co-operation and Development.
Yet even the French eclipse the Americans: the OECD finds 1.2m US-born citizens, out of a population of 300m, live overseas, making the US diaspora proportionally much smaller than the French or British.
While the legacy of empire has provided Brits with some choice destinations, this alone can't explain the difference. Dhananjayan Sriskandarajah, IPPR's director of research strategy, suggests the British are more outward-facing than other nationalities: "Brits care about international issues - it's in British newspapers. Whereas American and French societies are more insular." This, he says, helps explain why Britain has, in relative terms, one of the largest diasporas in the world.
If Brits, as Sriskandarajah says, do have a wider view of the world, then cheap travel and improved communications make abroad not as foreign as it used to be and emigrating less daunting.
In fact, for many middle-class families across the world, living abroad is a rite of passage, whether it is gap-year students digging wells in African villages, high-flyers studying for MBAs or investment bankers accepting foreign postings.
Dr Sam Scott, a lecturer in social geography at Liverpool University who has researched European migration, suggests the experience of foreign living and culture is a social aspiration and may be a way some families give themselves a mark of cultural sophistication. He says: "People's social and cultural experiences abroad are useful as a form of class 'capital'. It's about how you change as a person and the networks you enter that set you out as different."
The pursuit of this badge of distinction increases the likelihood of accidental migration, which takes place when the intention to return home is re-routed by, say, romance. Prof Hammerton suggests growing numbers of accidental migrants are making redundant the distinction of permanent migrants and short-term expats living overseas on a work posting.
How, for example, to define Ian Corfield? He is a 35-year-old chief executive of Bank West's retail division, who moved with his wife and two young children from central London to Perth after HBOS, which owns Bank West, offered him the post. "We always wanted to live and work abroad. We weren't sick of Britain; we just wanted to experience a different environment and culture," he says.
For the moment they're keeping their London house but think they might sell up and make Australia their permanent home, thereby blurring the demarcation between expat and migrant.
I ask Paul Beasley, editor of Emigrate, a magazine offering migration news and advice, why so many Britons want to leave. He says unemployment is not an issue but taxes and house prices motivate people to up sticks. "The property market is a big factor; they want their children to be able to get a foot on the property ladder. There is a dream, buoyed by the strong pound, that people can buy their houses outright abroad and have a nest egg."
Indeed, everyone I speak to at the fair raises the issue. At one stand, I ask what I could buy if I sold my one-bed London flat. "You could get a 3,000 square feet, four-bedroom house on an acre of land and three-car garage - a mini-mansion if you moved to Saskatoon," the Canadian consultant enthuses proudly.
Foreign homes allow us to experiment with migration. A survey by Barclays bank showed that 35 per cent of people buying a holiday home planned to relocate or retire there. David Bloor, a 49-year-old maths teacher from east Yorkshire, says that buying a property in Turkey has given him a taste for life abroad and now he hopes to settle farther away. Some commentators dub the fashion for buying overseas homes "pre-emigrating".
Professionals on overseas postings and Brits in possession of foreign properties are making British migration more middle class than it used to be, according to Prof Hammerton. He says traditional "migrations of austerity", when people felt driven out of Britain by hardship, notably in the postwar years and high unemployment in the 1980s, have given way to "migrations of prosperity" as people quit a Britain that is relatively affluent with high employment.
Prof Hammerton also says that migrants are both more wealthy and skilled than was the case in the 1950s. In part this reflects the fact that the middle class is bigger than it used to be and that tougher immigration policies in settler countries weed out lesser-skilled potential migrants, consigning the "Ten Pound Poms", British migrants who received financial assistance from the Australian government, to the history books.
However, if some Brits are migrating by accident after relaxing in their Provence holiday home or putting down family or work roots abroad, most people I meet at the Emigrate fair just want to leave Britain. There is something rather melancholy in visiting a fair with hundreds of people who want to leave the country.
Some of the would-be emigrants say they are fed up with Britain's "uncontrolled immigration".
The Elstons, a couple in their 30s from Nottingham, have been thinking of moving to Australia for the past 18 months. At first it was Canada, but then they changed their minds. "Canada and Australia are very different," I suggest. They shrug their shoulders. "It's more that we want to leave this country than go to another country. I pay too much tax. There are too many foreigners coming to this country due to EU restrictions being lifted," Mr Elston explains. I ask him if he doesn't see the irony that he will be an immigrant in Australia - the kind of person he is complaining about. He shakes his head: "I prefer other countries' immigration policies. They're controlled."
According to Paul Beasley, Gordon Brown's decision not to call an election until 2009 might exacerbate the exodus, not because of the prime minister himself, but because "when a political party has been in power for a number of years, people start to become disillusioned; they begin to feel that politics is a dead game".
But talk around the fair isn't just of policy and property. People at Emigrate speak of their motives for migration in therapeutic and emotional language. They want "space to breathe" to "get away from stress".
Beasley sums it up: "People just feel that life in Britain is becoming more stressful, more difficult. They believe that moving overseas will balance their lives and they will have much less stress."
I talk to Paul, a 43-year-old graphic designer who is planning to move to Australia with his wife and four children: "We want a better quality of life. I don't like Britain. My spare time is pressured. You live for your holiday. I want to be in an environment where the lifestyle is slowed down and you can take advantage of time to be with your family."
Paul's remarks appear to confirm Prof Hammerton's verdict that the "migration of prosperity" has replaced the "migration of austerity". Aspiration for a better quality of life these days need not be a hankering for increased riches but a reaction against the perceived stress of modern life.
Stress has become a "virulent epidemic" in British society, according to David Wainwright and Michael Calnan, authors of a study entitled Work Stress, published in 2002. The idea of being "stressed out" grips the nation. It radically alters how people look at work and the world around them. Work in pressurised Britain seems undesirable, and countries that appear to offer a more relaxed lifestyle are attractive.
Some people I met at the fair lusted for adventure but most were fed up and desperate for sunnier climes and eager to escape the stresses of life in Britain. So much unhappiness made me desperate to get away and I plonked myself in a mini-cab. It wasn't just me that felt infected by the visitors' discontent. "Everyone's been so miserable," my cab driver remarked. "I'll tell you what, we're better off without that whingeing lot. Give me the immigrants any day."
