It's now more than 12 years since David Cameron confidently told the Tory faithful that the Lib-Con Coalition Government would control Britain’s borders and keep net migration to below 100,000 a year; “no ifs, no buts”.

The political pressure on the then PM from the likes of Nigel Farage’s Ukip eventually led to the Brexit referendum and then a victory for those who wanted to “take back control”. Mr Cameron, having failed to keep his promise, left Downing Street.

Last year at one point net migration hit a record 504,000 – boosted by Ukrainians fleeing the Russian invasion and Hongkongers escaping the repression of the Chinese state as well as a rise in overseas students and 45,000 people crossing the English Channel. Next week, it’s widely expected the official figure for the whole of 2022 will be more than 700,000.

One Whitehall briefing document predicted that by the General Election next year, net migration could even top one million. A penny for Mr Cameron’s thoughts.

As Conservative nerves jangle, Jeremy Hunt, the Chancellor, insisted the UK Government was “completely united” on its approach to immigration. But no one believed him.

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Earlier in the week, Suella Braverman spoke at Britain’s answer to Trump World, the National Conservatism conference in London, where the Home Secretary declared: “You cannot have immigration without integration,” arguing that the “unexamined drive towards multiculturalism” was a “recipe for communal disaster”.

She was adamant the Government had to cut overall immigration by the 2024 General Election or the UK would risk “forgetting how to do things for ourselves” and she argued there was no good reason why Britain couldn’t train its own workforce of lorry drivers and fruit-pickers.

But less than 24 hours later, Mr Sunak told a food summit in Downing Street, attended by farmers and other food producers, that the increase in allowing more agricultural workers into Britain would continue. “I can confirm,” he told them, “another 45,000 visas for next year with the capacity for a further top-up of 10,000.”

When asked whose approach she agreed with, Environment Secretary Therese Coffey replied the PM was “clearly right” to make up to 55,000 visas available for the agricultural sector.

Over time, Mr Hunt argued, Britain should move away from its reliance on “unlimited, low-skilled migrants” but, presently, pragmatism was called for.

“What I’m trying to do is to make sure our businesses can find the labour they need to make sure recruitment isn’t a problem,” he explained. Official figures show there are 1m-plus job vacancies across the country.

An increasingly frustrated Home Secretary also appears to have lost the argument with colleagues on another front: students.

Cabinet failed to back her plans to remove foreign students if they failed to complete their courses and to cut the time they could stay in Britain once their courses had ended. Ministers also didn’t support banning them from bringing in family members, apart, that is, from those studying for a one-year master’s degree.

Gillian Keegan, the Education Secretary, was particularly hostile to Ms Braverman’s suggestions, stressing how foreign students brought great economic value to Britain.

Indeed, Professor Wendy Alexander, Vice-Principal of Dundee University, decried the “folly of jeopardising international student flows,” warning how prospective ones would “hear the hostile rhetoric and worry about what rules will be in place if they choose the UK”.

The former Scottish Labour leader added: “This impacts the flow of talent and the ability of employers to source talent.”

Her intervention came as a report underlined the benefit of overseas students to Scotland’s economy with the 2021/22 intake boosting it by almost £4.8 billion, underlining just how important they are to the survival of the nation’s universities.

It’s clear there are mixed messages coming from the UK Cabinet on immigration but, of course, Mr Sunak is, ultimately, in charge.

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Yesterday it emerged while on a flight to the G7 summit in Japan, he would not stand by the Tories’ 2019 pledge to see the level of legal migration fall, which it did briefly during the pandemic, but now looks firmly on an upward trajectory.

Stressing how he had “inherited some numbers,” the PM told reporters he wanted to bring legal migrant numbers down but declared: “Illegal migration is undoubtedly the country’s priority and you can see all the work I’m putting into that.”

Mr Sunak referred to this week’s Council of Europe meeting in Iceland, where he said he had made “another big step forward” with European Commission President Ursula von der Leyen to discuss the UK working with the bloc’s border force, Frontex.

So much then for Ms Braverman’s insistence that net migration must fall by the next UK election, likely to be in the autumn of 2024. It almost certainly won’t.

The irony will not be missed on anyone. That the great Brexit promise of “taking back control” over Britain’s borders has not been met and the levels of migrants has not gone down since 2016 but gone up.

Now it may be that, increasingly, many voters are relaxed about a higher level of net migration; it boosts the economy and is a compliment that so many people want to come and live and work here.

But it’s in those crucial Red Wall seats, where, we’re told, the issue of immigration is high on the list of people’s priorities, and where the next UK election could be decided; that is, between a minority Labour government and a minority Conservative one.

And even if Mr Sunak somehow manages to fulfil his pledge to “stop the boats” – which, as things stand, is still looking highly unlikely – it could be net migration to Britain will be anywhere between 700,000 and 1m people a year come the autumn of 2024.

One former aide to former PM Theresa May warned that abandoning the commitment to reduce migrant numbers would be a “potential electoral death-wish” for the Tories.

So, after 14 years in office, failure on this key Brexit pledge, could, ironically, prove to be the final nail in the Conservative coffin.