Three uniformed officers in stab vests bearing the title Immigration Enforcement drove their van down a quiet ­residential street and drew up outside a pebble-dashed terraced house.

A camera crew followed them as they went inside and arrested a young man, put him in handcuffs and led him outside to be locked in the cage in the back of their ­vehicle. Next stop was an equally undistinguished property – this one with the gate hanging off – where another man was detained and locked in the back of the van.

These were just two of a 'series of nationwide operations' conducted across the country in the early hours of April 29 as the then-Conservative government deployed 800 enforcement officers to round up scores of asylum seekers set to be flown to Rwanda.

The Home Office had identified an initial cohort of 5,700 people who could be sent to the African country and the effort to round them up – Operation Vector – was designed to last 11 weeks. But exactly three weeks after the first of the detainees had been arrested, the operation was brought to an abrupt end when the prime ­minister Rishi Sunak announced a snap election.

The rest, as they say, is history. Labour won the resulting poll by a landslide and, just 18 days after the vote, Home Secretary Yvette Cooper revealed she was scrapping key ­elements of the immigration laws introduced by the Conservatives last year.

Background papers from her department, which were not publicised at the time, reveal the startling consequences of that decision. Some 125,385 migrants whose ­asylum applications had been blocked under the Tories will now see their cases go ahead.

In other words, many who could have faced deportation to Rwanda under the Tories' now-abandoned asylum deal – and others whose cases were in limbo – now have the chance to win refugee status and every prospect of staying in Britain indefinitely.

The migrants arrested in April and May, who had been earmarked for the first flights, are all now understood to be free again.

This is despite the fact they were selected because they had the weakest asylum claims, as their applications had already been rejected and they had gone through the full and lengthy gamut of appeal stages, paid for, of course, by legal aid.

Many are thought to have returned to taxpayer-funded self-catering accommodation around the country, receiving £49.18 per head each week for food and essentials.

Others may be back among the 30,000 still in migrant hotels, where they are billeted – on a comfortable full-board basis – at the taxpayer's expense and also enjoy an allowance of about £9 per week.

The Conservatives attempted to end the use of four-star hotels but some are still in use and cost an estimated £150-a-night or more.

When the Mail visited one such migrant hotel in Peckham, south London, recently, the mood was buoyant. Asylum seekers living in some comfort in the Victorian red-brick property told us they were full of renewed hope following Ms Cooper's reversal of the Tories' plans.

'It's made a real difference for a lot of people,' said 40-year-old Ahmed, from Egypt. 'Every day we see progress.' Tariq, 33, a Jordanian who claimed asylum in March, heartily agreed. 'I'm glad things are moving forward,' he said, standing by the hotel's ornate black and gold wrought iron gates. 'It's given many of us new hope.'

And who can blame them for their new-found optimism? Since Labour took over, their chances of staying here have become a lot stronger. Shadow home secretary James Cleverly is far from alone in describing this new state of affairs as an 'effective amnesty'. That phrase is disputed by Labour sources, however, on the grounds that the Government still intends to remove failed asylum applicants from Britain.

So far, however, ministers have failed to explain in detail how this will be achieved, given all the legal challenges at the migrants' disposal. Labour's Human Rights Act, passed by Tony Blair in 1998, includes a 'right to family life', a clause frequently cited by immigration lawyers in successful arguments against removal. A client might have had children here in Britain, for example – meaning they can't be removed.

In the few short weeks since Ms Cooper's decision, many migrants have already received invitations to interviews with asylum caseworkers who will decide their claims.

Ahmed, who came to Britain on a visa in November 2023 then claimed asylum, told us: 'A lot of asylum appointments are being made and they are accelerating the process. Until the election, all the files were stagnant. But now the process is speeding up. I welcome it: People are getting their interview dates and decisions are being made.'

Ahmed was clear who to thank for this newly relaxed attitude towards asylum seekers like him.

'The new government is doing a good job,' he told us.

'Until they came in, nobody who had arrived from March 2023 was getting an interview. But now people who were coming as recently as last month are getting appointments, especially those from Syria, Sudan and Afghanistan [which have some of the highest acceptance rates for asylum claims].

'Some of the interviews now are done by video-conferencing, so you don't even have to have a face-to-face meeting.'

But while migrants like Ahmed welcome Labour's approach, the new Home Secretary's policy announcement deserves careful scrutiny. Her legal changes in July involved none of the blood, sweat and tears that accompanied the passage of the Conservatives' last stab at stopping migrants crossing the Channel by small boats.

The Illegal Migration Act 2023 triggered histrionic speeches in the House of Lords, the threat of a Tory split, late night Parliamentary sittings and knife-edge votes.

Ms Cooper, in contrast, made her changes at the stroke of a pen. She deployed a form of secondary legislation known as a 'statutory instrument', which can be put into force immediately and with little oversight.

The new legislation, the innocuously titled Illegal Migration Act 2023 (Amendment) Regulations 2024, runs to just 550 words – but is one of the most significant pieces of immigration law in years.This becomes apparent when the legislation is read along with its supporting paperwork.

This shows that of the 125,385 asylum seekers who arrived in Britain between March 7, 2023, and July 16 this year, no less than 40 per cent – just over 50,000 – would have faced removal under Tory measures.

This is because the Conservatives' laws contained retrospective measures barring any illegal migrant who arrived after March 7 last year from seeking 'lawful immigration status'.

In other words, any illegal migrant who came here after that date could not have an asylum claim accepted. But Labour has scrapped this retrospective element of the legislation.

The effect is that tens of thousands of migrants the Tories had planned to remove from this country will now have a chance to settle here permanently.

Even more startlingly, the documents predict that 54 per cent of the 125,385 asylum seekers will be granted refugee status by the Home Office at the 'initial decision' stage, but this figure could, in fact, be as high as 70 per cent. That's 88,000 people – the equivalent of a large town. Others who fail at the initial stage will go on to win asylum on appeal.

And there's more. The papers make clear that Labour's reforms will also benefit the 7,269 asylum seekers who have reached Britain since July 16, and those who arrive in the future – both totals that are not covered in the Home Office's calculations.

There could hardly be a more radical turnaround from the ­Conservatives' action plan to combat illegal migration.

On April 22, Rishi Sunak promised the first Rwanda removals flight would depart in 10 to 12 weeks. Seven days later, Operation Vector was launched.

Over the next month, around 160 migrants were arrested, it can now be disclosed, and moved to immigration removal centres ready to leave on the first Home Office charter plane to Kigali.

The Daily Mail can also reveal for the first time that the inaugural Rwanda flight was booked to depart on June 26 – 804 days after the scheme was announced by Boris Johnson in April 2022. Another flight was chartered for a week later, with more to follow.

But after Mr Sunak called the general election, all plans were put on hold at the insistence of the PM's Downing Street team.

Ex-Home Office insiders have told us that – had the election not been called – the Rwanda flights would have taken off, despite the prospect of last-minute legal challenges by some of those detained.

'There would definitely have been people on that first plane. It was going to work,' said one former aide. 'But No 10 didn't want flights to take off during the election campaign. Maybe they were less confident than us that it would work.'

The source added: 'Whether that would have changed anything in terms of the election result, I don't know. But it would have proved the concept of the Rwanda scheme.

'However, No 10 wanted to go into an election campaign where they could say: 'If you want Rwanda flights to take off, vote for us'.' When Ms Cooper announced her immigration 'reforms' to the House of Commons in July, she claimed the Rwanda scheme had cost the taxpayers £700million and boasted that, by changing the law, the Home Office could 'immediately start clearing cases from after March 2023', saving the ­taxpayer an estimated £7billion over the next 10 years.

But her figures have been hotly ­disputed. The Home Office has admitted that its calculations did not take into account the 'wider impact across the immigration system', nor did it ­consider how handing migrants permission to stay would affect Britain's job market', wage levels or the impact on public services.

After all, once asylum has been granted, much of the cost of supporting migrants passes from the Home Office to beleaguered local councils. Moreover, migrants whose claims are finally rejected are still funded by the taxpayer, under rules that forbid the Home Office from leaving people destitute.

Conservative MP Nick Timothy has described Ms Cooper's £7billion claim as 'clearly ridiculous'.

In April, the pro-migrant Refugee Council lamented that, by the end of the year, more than 115,000 ­asylum seekers would have been affected by the Tories' tough ­policies.

But the new Labour Government's own figures ­suggest that an even higher number of migrants are already benefiting from Labour's reversal of those measures.

Migrants who once faced removal under the Tories now have a strong chance of being able to remain in Britain indefinitely. Some may, indeed, end up making a net contribution to Britain's economic and cultural life.

But shadow minister Mr Cleverly, who also hopes to be the next Tory leader – with a re-introduction of the Rwanda scheme among his policies – insists that Labour's generosity comes at too high a cost, particularly in the Channel which just this week saw another 12 deaths, including six children and a pregnant woman.

'Labour are allowing thousands to apply for asylum and granting the same right to any who arrive here illegally in the future too,' he told the Mail.

'They have ditched our Rwanda partnership and our best deterrent, opening our borders to the people-smugglers... and there is still no sign of their phantom ­Border Command.

'Labour do not care about controlling our borders.'

Back at the Peckham hotel, Tariq from Jordan says that in the wake of Ms Cooper's decision, he has already received an appointment for his asylum interview.

Another resident, 27-year-old Zia from Afghanistan, came here on a ­student visa in February last year on the understanding he would do a master's degree in international business management.

Instead, he lodged an asylum claim just weeks later, he says, after the Taliban barred its citizens from sending more than £230 per month out of the country, meaning his father was no longer able to fund his living costs.

'I'm glad the new government has made changes to the system and I hope to get my asylum interview soon,' he told us.

'I still have my father, a brother and three sisters in Afghanistan.

'If I'm successful in that, I hope that one day I can bring my whole ­family to Britain.'