Keir Starmer’s plan to drastically slash net migration could fail, the Government’s leading advisers have warned.

The Prime Minister wants fewer companies to hire foreign workers and to boost domestic workers’ skills.

But Professor Brian Bell, who predicted net migration will remain at 300,000 for the “next 10-20 years” warned Sir Keir that his plans “were not guaranteed” to deliver “large falls” in net migration because a lack of skills was not always the primary driver.

The advisers said it was often poor pay and conditions which put off British workers.

The Migration Advisory Committee, in its annual report, revealed the influx of migrants on health and social care visas has led to more foreign workers on low pay.

Professor Brian Bell, Chair of the Migration Advisory Committee, said: “We know that recent figures have shown net migration falling.

“This has been driven both by government policy changes and by other factors, such as the impact of enhanced enforcement of the genuine vacancy test in the care sector.

“Whilst we are expecting net migration to fall further, we would caution the government against seeing linking immigration and skills policy as a one-size-fits all approach to bringing down net migration and encourage them to continue to consider individual circumstances within sectors.”

Going further, Professor Bell told the Daily Express: “I don’t think the Home Secretary thinks of it as a panacea.

“The one good thing that is happening here, is they are saying ‘look, if we can get the skills right, we can get skills training right in the UK, there will be more people who employers can employ here than looking international.

“Where one has to be cautious is seeing where that really affects immigration. If we can successfully train more nurses in the UK, that will have a really significant effect on immigration.

“I don’t think anyone thinks the reason the NHS goes to the Philippines to recruit nurses is that we think they are so much better than British nurses. There just aren’t enough British nurses.”

Professor Bell’s report added: “If the government wants a functioning health and care sector, with lower reliance on immigration, more still needs to be done to fill roles domestically through increased funding to improve pay and conditions.

“This important trade-off must be considered when designing migration policy and a point we have repeatedly made.”

Net migration hit a new record of 906,000 last year, heaping more pressure on housing, schools and GP surgeries.

The Office for National Statistics said net migration to the UK hit 906,000 in the year to June 2023, amid an influx of foreign students, a spike in non-EU workers, particularly in the health and social care sectors and the introduction of the Ukraine and Hong Kong refugee visa schemes.

Professor Bell said that he thinks numbers will “come down quite rapidly”, and could settle at the 300,000 mark as an average for “the next 10-20 years”.

He added: “It’s what we expected, and therefore I think we’ll see those numbers come down quite rapidly. And it’s always dangerous to predict that, because as soon as you say that, the numbers will get revised up again.

“But I think […] we can be confident that we’re going to get down to the sort of levels that we think will be the long run – without any further policy changes – of about 300,000.

“I think we can get there in the next two to three years probably.”

Pressed further on how long he thinks the figures could settle in that sort of range for, Professor Bell added: “We think of 300,000 as being if you didn’t change policy anymore, that’s probably where we’ll settle.

“And you should think of that as being the average for the next 10 to 20 years. In the same way that in the last 10 to 20 years, it’s averaged about 200,000-250,000 – so a little bit higher than previously.”

Professor Bell warned previous promises to introduce a target had hit trust in the immigration system.

He told the Daily ExpresS: “One of the failures of policy, particularly in the 2010s, was announcing a target and then consistently missing it.

“That does nothing to enhance public trust in the immigration system.

“If you decide, as a Government, that you want to have fewer work migrants, then you can introduce a cap.

“But if you introduce a cap, the problem is the arbitrary nature of what’s imposed. Do you just do it on a first come, first served basis? Do we prioritise some sectors?

“In the past, we have tended to say, if you are going to change the numbers, probably the right way to do it is to move the salary threshold. Moving the salary threshold means that if we are going to restrict the numbers, at least we are going to let in the highest paid.”

Migration Watch Chairman Alp Mehmet said: “The MAC is right to say focusing just on skills policy will not be enough to bring down net migration from its catastrophically high levels.

“And while it may appear to be falling, a “provisional” 728,000 for the year to June is still way too high and totally unsustainable. Even half this figure will lead to millions being added to our population – 9 million in the next 25 years.

“The government must shake off its complacency and urgently bring in policies that lead to balanced net migration.

“An overall cap, firm action on those spinning out temporary stays, and a serious enforcement effort are all essential if net migration is to be drastically reduced.”