In 2015 Nigel Farage admitted a preference for migrants from “India and Australia” over those from “countries that haven’t fully recovered from being behind the Iron Curtain”. It is not a view shared today: the British are more welcoming of Polish immigrants than almost any other nationality. According to YouGov, more of us today think they make a positive impact (53 per cent) on life here than we do of Indians (35 per cent), Germans (50 per cent) and Americans (40 per cent).

Yet Poles are becoming increasingly scarce. At the time of the Brexit vote in 2016 a million were living in Britain, lured under free movement by substantially higher UK wages. By 2021 a third had left.

For most young Polish people, staying put has become a much more attractive offer — something not lost on Kemi Badenoch. “We are competing with economic success stories like Poland,” she told the Tory conference last week. “Fifteen years ago Polish workers came here to find opportunity. Now Poland is growing twice as fast as we are.”

Twice does not quite cover it. In 1995 Poland’s GDP per capita was $13,600 in today’s money — about 36 per cent of Britain’s and roughly the same as Brazil’s. Today Poland’s figure is $44,500, or 81 per cent of ours. It may soon pull level. Since the end of 2019 Britain’s GDP per capita has grown by less than 1 per cent in real US dollars. Poland’s has grown almost 18 per cent, nearly twice as much as that of the US.

• How Poland became one of Europe’s biggest success stories

How has Poland done it? Since the fall of communism, it has looked westwards: instead of selling off state-owned assets to a small number of rich individuals, Poland held public offerings and encouraged foreign ownership. More recently it has enjoyed the sweet spot of being in the EU but maintaining its own currency.

The brain drain of young talent to countries like Britain and Germany was a problem throughout the 2010s but several factors have turned things around. Since 2019 Poland has had a lower income tax for workers under 26; a recent study found it to be the third-best European country for young adults to live in. Manufacturing, led by car production, remains important, but its tech sector is thriving, with many workers who have returned from abroad. Wages, adjusted for prices, are now neck and neck with those in Italy.

And while it will take Britain a decade to raise defence spending to 3.5 per cent of GDP, Poland did it almost overnight: this year it is expected to spend the equivalent of 4.5 per cent of its economy on its military, up from 2.2 per cent in 2022. It has been funded by borrowing, which until recently was modest: debt has hovered around 50 per cent, compared with 96 per cent or more in Britain, America and elsewhere.

So the Polish economy is growing fast. Isn’t that what we would expect? Economists often talk about “catch-up growth” — the theory that poorer countries grow faster. They have lots of easy ways to boost productivity, like buying better equipment and investing in better training for staff. Richer countries like Britain have (supposedly) done all of that stuff already. The only way we can boost our economy, the catch-up theory goes, is by new technological discoveries.

However, a closer look at the growth figures suggests Britain might have more to learn from Poland than we think.

Data from the EU tracks economic activity right down to the regional level. Strikingly, it reveals many parts of Britain have been overtaken by Poland’s more successful areas. The greater Warsaw region has a GDP of €67,000 per capita, adjusted for prices, which is bettered only by central London.

Capital cities typically have strong economies. But 12 of Poland’s 17 regions are now richer than west Wales, the poorest part of Britain. Dolnoslaskie — or Lower Silesia — in Poland’s southwest is better off than Greater Manchester. In fact if we were to strip London out, Britain’s output per head would be just 3 per cent ahead of Poland’s.

Never mind catching up: in some ways Poland is already ahead. The country has faster mobile internet, cheaper electricity and more high-speed rail. Britain has been rich long enough to develop complex planning laws, notes David Lawrence of the Centre for British Progress think tank; developing countries like Poland just build because they see it as essential to prosperity.

Britain has been talking about a third runway at Heathrow for decades: the latest proposals will cost £49 billion be complete in 2040 (although I wouldn’t hold your breath). Poland expects to open a new central transport hub — with two runways and a high-speed rail link, serving 45 million passengers a year — by the early 2030s for £30 billion. When it comes to investment, particularly in its regions, perhaps Britain is the country that needs to catch up.