"It was mainly for my wife and kid," says Josen Jose, 37, an Indian engineering technician who moved to Edinburgh with his family in 2021. "I wanted a better life for them. I'm from Kerala in India, but before coming to the UK I worked in the Middle East for 15 years. It is not easy there for women with regards to jobs and education. I felt she needed more rights and freedom. She came here on a Masters and I joined her."

Jose and his family are in the vanguard of an unprecedented surge of immigration to the UK, the scale of which was hammered home last week by new ONS population statistics. The figures suggest the British population has overtaken that of France, for the first time. On current trends it will grow to 72.5 million by 2032, an increase of 7.3 per cent from a decade earlier, or just under five million, and beyond to 76.6 million as we near the middle of the century.

As Britain's birth rate is below replacement levels, and with 4.9 million people forecast to emigrate in the coming years, the net population growth will be entirely driven by the arrival on British shores of nearly ten million migrants, five million of whom have already arrived.

Whereas the previous wave of mass migration to the UK was mainly European, after 10 new countries joined the EU in 2004, the coming millions will be mostly Indians, Pakistanis, Nigerians and Chinese nationals, arriving on student visas, work-study visas, social care visas and under the new points-based immigration system.

How will they reshape Britain? Do the next seven years spell demographic catastrophe or economic boom? The sense of change is already palpable, the most obvious sign being the dramatic rise of Reform UK, a party advocating a freeze on net migration, to lead the polls.

"By 2050, one in three of the UK population will have been born abroad," says Karl Williams, Research Director of the Centre for Policy Studies, a think tank. "Regardless of where those people come from, that's a huge amount of churn, and something that is completely unprecedented. That's where a lot of the worries around immigration come from. It's that sense of disorientation, that things are changing around you really quickly."

On the latest projection, by 2032, 14 per cent of the whole UK population will be people who have arrived in the 10 years leading up to it, practically all of them from India, Nigeria, Pakistan and China. They are moving mostly to the big urban centres - especially London, Leicester, Reading, Oxford and Cambridge.

The anticipated influx will mean five million more people needing somewhere to live, transport, healthcare, education and every other kind of public service, at a time when national infrastructure is already straining. More than 6 million people sit on NHS waiting lists. A&E departments are buckling under record-breaking delays. There are shortages of teachers and overcrowded classrooms. Three quarters of the population believe public services have deteriorated in the past five years. There is a backlog of more than 4 million houses.

Meanwhile, 11 million people - a quarter of Britain's working age population - do not have a job, and 3.2 million are on sickness and disability benefit, a million more than before the pandemic.

Faced with these numbers, successive Conservative governments promised to get to grips with migration levels. The statistics told another story. Boris Johnson's immigration reforms after Brexit - which introduced a points-based system as well as new work-study and social care visas - led to net migration figures of an astonishing 906,000 in the year ending June 2023. Keir Starmer has promised to bring numbers under control, but there is yet to be much evidence his Government is succeeding.

"This is more than worrying," wrote Migration Watch on X, in response to the ONS projection. "It's an unfolding disaster."

Chris Philp MP, the shadow Home Secretary, says: "I'm horrified by these forecasts. Migration at this level will put a huge strain on housing, transport and public services. Migration at this level will inevitably be low-skill, low-wage, reducing productivity and likely being a net drain on the taxpayer. Immigration on this scale also creates social tensions, given the very poor track record of integrating new arrivals into British society."

The ONS is quick to caveat that their data is a projection based on past data. It could be brought down by policy or other factors, although it could also be bumped up by unexpected events: Hong Kong and Ukraine are recent examples, but who is to say there won't be another urgent refugee crisis originating somewhere else?

Based on the available data, however, the 10 million new arrivals by 2032 will mostly be students and low-earning, unskilled workers, destined for the social and care sectors.

Following the accession to the EU of 10 new countries in 2004, including Poland, Latvia, Lithuania and Estonia, net migration to the UK hovered around an average of 250,000 before Brexit.

For obvious reasons the number dropped during Covid, before an extraordinary resurgence after Johnson became Prime Minister, despite his promises to get immigration under control. "We will restore democratic control of immigration policy after we leave the EU," he said. "We must be much more open to high-skilled immigration, such as scientists, but we must also assure the public that as we leave the EU we have control over the number of unskilled immigrants coming into the country."

The result has been the opposite.

Economists say that for all his government's good intentions, it was obvious that migrants would respond to Johnson's policies by acting in their economic self-interest. who specialises in migration, was one of the authors of a MAC (Migration Advisory Committee, a body which advises the Government) report in 2018 on the proposed new visas. Of particular concern were the work-study visas, which gave students the right to work in the UK for two years after they finished studying. "We discussed it because the universities were lobbying for it, and we said 'be careful', because if you do that, the work rights become very large relative to the value of the education," he says. "You'll see a big rise in Masters' students, a big rise in lower-quality institutions, dependents and so on."

This is exactly what came to pass. Last year, the UK gave out 1.1m visas to students, workers, family members and other groups, such as refugees from Hong Kong and Ukraine, according to the Home Office. There were 426,150 students, 181,846 NHS and care visas, 127,228 skilled workers and 57,341 partner visas issued. Skilled visas were dominated by Indians, Pakistanis and Bangladeshis; just 14.1 per cent came from the EU. Of NHS and care visas, 53.9 per were given to nationals from Asian countries and 38.6 to those from African states.

According to the ONS, the net migration figure will continue to decline from its post-Covid peak until 2028, but thereafter will remain at 340,000 per year as a long-term average.

"In immigration policy, often the government writes a set of rules saying 'we want this visa to achieve this, and quite legitimately migrants or potential migrants would seek to use these rules to suit them," Manning adds. "I mean, what do we expect? They're not doing anything illegal. Nobody in government thinks 'what could go wrong with this?' Often immigration policy has been a failure to do due diligence. [...] They opened up social care but didn't have a system in place to check people were complying, or that the employers applying for these visas actually had jobs for these people. A lot of time agencies would only have work for their people occasionally. There was just basic stuff that [the government] were not doing."

Once migrants arrive in the UK, there is the question of whether they are net contributors to the government coffers. With falling productivity and an ageing population, Britain is desperate for growth. On balance, will the 10 million arrivals be a help or a hindrance?

"Migrants as a whole pay in about as much as they take out," says Ben Brindle, from Oxford's Migration Observatory. "But there are differences between different groups. More important than how many are coming is who is coming to the UK. Those coming to work in higher-paying roles tend to have a positive impact on the public finances. International students tend to have a positive impact. But those without jobs or in low-paying jobs tend to have a negative impact. This is a challenge for a government looking to reduce net migration, because the types of migration that can be influenced by policy are work migration and study migration. Whereas those that are less beneficial, like family migration or asylum, are more difficult to influence.

"I'm not sold on the idea that migration is the answer to an ageing population," he adds. "They're not likely to address the fact that [Britain needs] increased spending on healthcare and pensions. Also, the levels of migration we'd need, even if they did have a positive impact on finances, would need to be rather high, probably implausible."

As well as their impact on the economy, 10 million new arrivals will reshape British society, too. The pace of change is comparable to the biggest migrations in history. In 1907, at the peak of immigration to the US, Ellis Island processed over one million arrivals; the annual rate Britain can expect. Just as those arrivals are still clear in American society, Britain will be feeling the shifts for decades.

The flow of migrants the ONS projects over the next decade will make Britain more younger and more ethnically and religiously diverse.

Those arriving over the past 20 years have tended to have a stronger faith than the existing British population. For Grace Davie, professor emeritus of sociology at the University of Exeter, this means the trends she was taught when she was younger no longer apply. "Migration makes a difference," she says. "When I learnt my sociology forty years ago, I was taught that religion would ebb from the public sphere but persist in private lives. At the moment you see a decline in both private religion as well as public religion. Because of migration and the need to manage diversity, religion is more prevalent in public life than it was two decades ago."

According to the ONS projections, the majority of migrants by 2032 will be from Christian Nigeria, Muslim Pakistan and Hindu India. This is in contrast to the migrants after 2004, which tended to be white Christians. Among asylum seekers, which make up a small proportion of the total numbers arriving in the UK, the overwhelming majority come from Muslim-majority countries. There were 99,790 applications for asylum last year, the highest number on record, including 9,560 from Pakistan, 8,453 from Afghanistan and 7,895 from Iran. In contrast to the precipitous decline of the Church of England, recent migrants tend to be more devout, bringing new and well attended places of worship.

"It isn't self-evident how you manage [the religious mix]," Davie adds. "Because we're secular, we manage this very badly. Not only have we lost the sensitivities to religious life, we've also lost the knowledge that goes with it and we're not equipped to set up good processes or mutual understandings to deal with diversity. You end up with an ill informed and ill mannered conversation. If these projections happen, it will be more of the same. It's extremely worrying."

If migrants are more religious, they are also younger and better educated. Some believe that migrants are a vital demographic shot in the arm. Compared to the rest of the population, according to Migration Observatory, migrants "are more likely to be of working age or have a university degree."

There are plenty who argue that migration is the best solution to the demographic challenges facing practically every advanced economy. With the birth rate below replacement and a bulging population of non-working older people, policymakers are aware of the need for working-age people to support them. Christian Dustmann, a professor of economics at UCL, who is from Germany himself, argues that Britain is better placed than many other nations. "The UK has a demographic development which could be the envy of many European countries," he says.

"In Germany in particular, but many other countries, demographic change will cause a substantial decrease in the working population. The UK is relatively stable. From a pure economic perspective this is an easier situation to handle than decline. But the question is always how do we avoid potential unhappiness of the native population?"

In contrast to what Chris Philp says, Dustmann argues that "the UK has been pretty exemplary in integrating those communities into the wider society", although concedes there are "serious challenges" to the numbers projected by the ONS. "There are attempts to reduce migration by the current government, but at the same time you want to grow. How do you grow if you don't make available to industry the workers it needs? How can we build housing stock without builders?"

Perhaps the greatest impact of the unfolding wave of migration will be felt on public services in the areas - especially London - which will see the largest numbers of arrivals. People are more fluid than infrastructure, which means they can arrive faster than new services can keep up.

"You can make the argument that the per capita ratio of doctors to patients is just about holding steady," says Williams. "But while you can bring skills and a work ethic, you can't bring a new GP surgery or a mile of road."

Housing is the most acute concern. "Housing, infrastructure, roads and railway systems are a lot slower to respond when there's an increase in demand," agrees Ben Brindle. "Things would look very different if there were higher rates of housing."

Unlike the Eastern Europeans who preceded them, who were more evenly distributed, recent migrants are congregating in the urban areas where there is already the most acute shortage of properties. "We know that about 90 per cent of migrants come to England and about 40 per cent come to London, which is where we have the biggest [housing] shortage," says Williams. "We did some research and found that over 2013-2023, net migration had created a need for 1.2m houses."

Generally speaking, migrants will go where the jobs or studies are, which tends to mean the capital. According to the 2021 census, 27.9 per cent of Westminster had arrived since 2011, 25.3 per cent of Kensington & Chelsea, 25.2 per cent of Newham and 24.5 per cent of Tower Hamlets. In central Luton, a striking 46 per cent of all residents had arrived in the past decade. Contrast that to South Staffordshire, or north-east Derbyshire, where just one per cent of the population arrived in the past decade.

Even recent arrivals are noticing the stresses on infrastructure. "From outside the UK, everything seems to be OK in the UK," says Josen Jose. "There is a painted picture of a developed country, but when you come here you find things are not quite as expected. There are some issues. There is a cost of living crisis. In the Middle East you are without taxes; but here you are compensated by free education and healthcare. But again, there are gaps. [...] We come here, we pay taxes, and we also have to pay NHS health access charges and visa fees for which we take loans, which have to go on for months to pay back."

He adds that the low pay and high cost of living in the UK mean that many of the families in his community are considering moving again. "Most of our community members are NHS staff - nurses, mostly - and [many] of them are migrating to Australia because there, a one person salary is enough to feed the family."

This enormous, messy, unformed wave of migration is still in its infancy but it has already helped to dramatically reshape British politics. Voters frustrated by economic stagnation and the traditional parties' repeated failure to limit migration are looking to Nigel Farage. Reform have pledged a complete freeze on non-essential migration. Over the past fortnight, successive polls have shown them leading Labour and the Conservatives.

This week, Reform's chairman Zia Yusuf told Nick Robinson that the immigration figures mean "history will judge Boris Johnson as one of the most damaging prime ministers in this country's history."

The violent protests in response to the Southport killings, and the dramatic rise in anti-Semitic attacks since October 7 2023, show that the threat of sectarian violence is not far below the surface in the UK. Extremist politicians of every side will use increased migration as an excuse to stoke the flames: Tommy Robinson being jailed for false statements about a Syrian refugee is only one obvious example.

Whatever the effect of increased migration on our politics in the longer term, a large proportion of those arriving in the country are unlikely to have a say themselves. Net migration of 5 million by 2032 does not, after all, mean five million more voters, says Rob Ford, professor of political science at Manchester University. "These projections do not have a very good track record," he says. "They have been very wrong before. But with that mind, what does it all look like? Point number one is that the largest group in this is politically close to invisible, which is students in British universities. Many of them technically could vote if they have Commonwealth citizenship, but on the whole they don't. And the largest group, the Chinese, don't have the ability to do so."

Then there are the labour migrants, who might be more interested in voting once they have been settled for a few years. "Historically labour migration to Britain has often been at the bottom end of the labour market," Ford says. "But on average, [recent labour migrants] are further up the income spectrum than past waves of migration. That would tend to pull people in the direction of the right, but the kinds of jobs they are doing in the public sector tend to pull people to the left."

He adds that even long-term migrants do not always become voters. There is no Polish vote, he points out, even 20 years after the wave of Polish migration began. "If they had arrived on the same terms as Indians in the 1960s they would have been a massive deal in the last couple of elections because they are evenly spread, which means every MP would have to worry about what their local Polish constituency was thinking."

A recent report from the Institute for Public Policy Research, or IPPR, recommended that the Government should give the vote to five million foreign nationals currently living in the UK. On historic voting patterns, such a move would favour Labour. But it is no longer so clear which way migrants would vote. Recent studies have shown that aspirational ethnic minority voters are increasingly turning away from Labour.

While migration is clearly rising towards the top of the political agenda, for all the increasingly spiky rhetoric around the numbers, Ford points out that Britain has a long history of welcoming new arrivals. Most Brits live happily in diverse populations. "This is not to say racism or Islamophobia are gone from society," he says. "But nobody is going to be putting out signs saying no blacks, no dogs, no Irish. One of the things that shaped the tendency of first generation migrants to be very Labour was race and racism. This was the era of Enoch Powell. We have Tommy Robinson and... whatnot today, but the intensity is much lower. It won't be lost on a Nigerian migrant that a Nigerian migrant is the current leader of the Conservative party and that the previous leader was a Hindu Indian. Hindus swung Tory at the last election."

Human habitation in Britain dates back at least 800,000 years, according to archaeological finds in Norfolk 10 years ago. The first 10 million came slowly. By the time the first official census was conducted in 1801, there were 8.9 million people living in England. The next 10 million are arriving in a decade. While there have been surges of immigration in modern British history, they mostly have been a fraction of the scale of the current situation. In the late 17th century around 50,000 Huguenots arrived. Hundreds of thousands of Irish in the late 19th and early 20th century. At the peak of the post-1948 immigration wave from the West Indies and South Asia, the average was around 50,000 a year.

Sunder Katwala, the Director of British Future, a think tank focussed on migration, argues that immigration to Britain tends to be harmonious, but only after a substantial lag.

"The big numbers scare people," he says. "But the lived experience of this is we do it OK, with a lag effect of a generation or two. We can manage it quite well if we're actively managing that. But people doubt that. They think 'will I get heard in a society that's changing that fast?' But I don't think it's one of these hell-in-a-handcart crash multiculturalism things. If you look at high diversity places, in the cities, they feel they're doing OK. It's the places of lower pace of change that feel they're being left behind. It's more a polarisation risk than the idea it's not handle-able."

The polarisation is already obvious. Reform UK, who have promised a complete freeze on net migration, are surging ahead in the polls. On current trends, voters are not in a hurry to forgive the Conservatives for promising one thing on immigration and doing another.

The ONS projections make the looming scale of the migration wave plain for all to see. Britain is undergoing an unprecedented experiment in changing its population. The results will be felt for years: in the economy, in public services, and in politics.