Back in 2016, in the run-up to the EU referendum and as Leave campaigners promised to “take back control” of our borders, chief Brexit cheerleader Nigel Farage promised the British people that leaving the European Union would allow the UK to cut net migration to below 50,000.

He wasn’t the only one to promise to drive migration down. David Cameron and Theresa May promised to cut net migration to the “tens-of-thousands” while Boris Johnson promised in 2019 to reduce the net migration from the-then 226,000 a year.

Instead, seven years after the UK voted to leave the European Union, net migration has hit a record high of 606,000 in the year to December 2022, while illegal migration has quadrupled from just over 13,000 in 2018 to more than 52,000 last year.

Politics live: Record net migration Q&A

Out of control might be a better three-word slogan for the current state of affairs that puts huge pressure on the Conservative government that now owns this mess.

Because it’s easy to make the promise but fiendishly hard to keep it.

As migration numbers published today show, it’s difficult for a government in desperate need of economic growth to choke off the supply of Labour without hurting the economy, with work visas accounting for a quarter of all visas granted in net migration figures.

Opposition figures have easy answers: Mr Farage told me he was “hand on heart” not being dishonest about the promises he made in the 2016 Brexit referendum, including cutting net migration to under 50,000, as he told me the Tory government should accept worker shortages to cut immigration, knowing he’d never have to implement a policy of economic self-harm as the government looks to stave off recession and bring down inflation.

Yvette Cooper, the shadow home secretary, told me she would re-train British workers to fill jobs currently being done by foreign workers as she spoke of “unusually high levels” of legal migration and linked it to the “chaos” in the Home Office, lambasting the Tories for the “continual massive gap between the rhetoric and reality”.

But, again, when I asked her to commit to reducing work visas to below 300,000 over the course of a five-year Labour government, should Sir Keir Starmer win the next general election, Ms Cooper declined.

You only have to look what her predecessor and Labour party chair Annelise Dodds said on the matter to understand why: “Potentially, in some areas, where there’s a short-term need for skills, you could see in the short-term, actually, people who are coming in, increasing in number.”

What is clear is that the Conservatives – the party of Brexit and of successive promises to drive down net migration – is under huge pressure to tackle this issue, from within its own ranks and from many of its voters who feel let down.

And that pressure falls on the shoulders of Rishi Sunak, who was clearly uncomfortable with repeated questions about migration numbers at the G7 in Hiroshima last week.

So he should be. A politician who tells aides he’ll only promise what he can deliver, and deliver what he promises, he won’t recommit to the 2019 manifesto pledge to drive net migration below 226,000.

Instead he told me in our interview in Japan, he’d reduce migration below the “figures he had inherited” – so around the 500,000 mark, although he refused repeatedly to actually utter that figure in our interview.

At face value, he may well be able to drive down the 606,000 to that level ahead of the next general election, given that 114,000 of those migrants in 2022 were Ukraine refugees, with a further 68,000 visas granted to dependants of those in the UK to study – an area where the government announced it was going to clamp down this week.

But is driving legal migration below half a million – still double your manifesto commitment of 2019 – really something to crow about? Mr Sunak clearly knows it’s not and has instead made stopping illegal small boat crossings his priority.

That too comes with huge risk, and the data out on Thursday shows it.

Asylum claims are up 25,000 to 75,000 on last year – the highest in two decades. The backlog of claims is 172,000 and when it comes to small boat crossings, only 504 of the over 40,000 claims have received a decision.

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Housing tens of thousands of asylum seekers while they await decisions; co-operating with France and EU neighbours to help police the coastline and break up the smuggling gangs and stop boat crossings; having somewhere to send failed asylum seekers when Brexit means you no longer have return agreements with EU countries; setting up a Rwanda scheme which has yet to be in operation and plagued by legal difficulties.

Those close to the prime minister will tell you privately of the conundrum.

These boat crossings are a political problem that must be tackled, but success is so dependent on external factors that the government can’t control.

One senior figure told me that at the very least the prime minister must go into the next election at least having a narrative about how he tried to tackle small boats, even if part of that story ends up being that he was thwarted by Brussels, Paris, the EU courts, or lefty lawyers.

Stop the boats; take back control; tens of thousands – such easy slogans to create, fiendishly hard policies to actually implement as the current prime minister all too well knows. That’s why he won’t own his predecessors’ promises – and he might well come to regret his own.