If we instead take purchasing power parity as the measure, which attempts to adjust for the fact that the cost of living is substantially lower in Poland than Britain, then Poland is already richer than the UK – $49,000 per capita against $47,000. That gap is forecast by the IMF to widen further over the next five years to $63,500 against the UK’s $50,000.

Yet one thing that Tusk has definitely got wrong is attributing the difference to membership of the European Union. This has of course been extraordinarily advantageous to Poland, so Tusk is bound to be generous in handing out the credit. 

Nor is it just because Poland has had the benefit of very sizeable net transfers from the rest of the EU to help the country modernise and catch up. 

As part of Europe’s single market, it has also enjoyed the advantage of a relatively low-cost labour force, prompting many European companies to locate operations there. It’s on the whole much cheaper to manufacture in Poland than it is in Germany and France. The workforce tends to be younger and more compliant.

What’s more, Poles have been prime beneficiaries of the single market’s core free movement principles. For this, Mr Tusk owes the UK a huge debt of gratitude. Unlike much of the rest of Europe, including France and Germany, Britain allowed Poles the right to live and work in the UK with immediate effect on accession in May 2004. 

This could theoretically have been quite bad for the Polish economy. Hundreds of thousands of Poland’s prime working age population leapt at the opportunity to live and work in Britain, Ireland and Sweden, the only EU countries not to impose restrictions.

Yet in practice, the constant toing and froing proved a powerful driver of economic growth in Poland, which gained valuable expertise from returning migrants and enjoyed a steady stream of remittances. The stories were possibly apocryphal, but whole Polish villages were said to subsist on the largesse of British tax credits and welfare payments.