It sounds like the start of a bad joke. What do Boris Johnson and Silvio Berlusconi have in common? Yes, apart from that. And that. Oh, and that too. Well, both have also warned of the dangers of too many foreign footballers. Johnson, of course, blamed England’s Euro 2016 humiliation on huge numbers of international players “soaking up space on our top teams” while Berlusconi has spoken about how he craves an all-Italian Milan side.

Johnson may have been trying to tap into the nation’s worst instincts, singing his siren song when the country was vulnerable after the Brexit referendum. Yet more sober heads, such as Paul Scholes, have also warned that too many foreign players could damage the England team as youngsters are unable to break through. The Football Association agrees. As things stand, Premier League teams can register up to 17 non-home grown players in a 25-man squad, a figure the FA wants reduced to 13 after Brexit.

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Yet, while watching Gareth Southgate’s new England buzz through the Czech Republic defence on Friday, it was impossible not to wonder whether such fears are overblown. And digging a bit deeper, across wider sport and industry as well as football, that feeling only grows. Because all the evidence suggests foreigners do not damage national teams. If anything, they improve them.

One of the largest studies into the factors behind a country’s success in international football found – unsurprisingly – that, all else being equal, countries with larger populations and higher GDP per capita performed better in Fifa’s rankings. Yet, tellingly, the researchers Michael and Marikova Leeds noted that bringing more foreign players into a domestic league tended to lead to an improvement in an international team.

As they noted in their conclusion: “When countries contemplate how best to advance in international soccer rankings, they should not be afraid to import players for their domestic league. Because the stronger the structure and performance of the domestic league, the greater the country’s international success.”

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Why might more foreign players be an advantage? One explanation is down to what academics call the spillover hypothesis. As David Forrest, an economist at the University of Liverpool, explains: “If you bring in a foreign star, then home-grown talent benefits in two ways. First, because they have a more talented colleague to learn from. And, second, because foreigners may bring in different ways of doing things, thus broadening ways of solving problems.”

Examples abound in English football. The Class of 92 have spoken about how Eric Cantona’s professionalism and ability at Manchester United lifted them to another level. Arsène Wenger revolutionised Arsenal after the bumpy reign of Bruce Rioch. And who knows what is happening in an alternate universe where Mauricio Pochettino did not take over from Tim Sherwood at Spurs?

It is perhaps also notable that nine of England’s starters at last year’s World Cup played for either Pep Guardiola, Jürgen Klopp, José Mourinho or Pochettino. It was a youthful and inexperienced team, with far fewer starts historically than most England squads, yet their performance was one of the best in a generation. Absorbing from the best at club level surely helped them with that accelerated learning.

Forrest, incidentally, was part of a massive study that examined the effects of foreign players in 47 European basketball leagues on their national teams between 1986 and 2008. Again the results were clear. An increase in the number of foreigners in a domestic league tended to generate a subsequent improvement in the performance of the national team when it came to qualifying for, or competing at, the European and world championships and Olympics.

The authors assessed the supposedly negative effects of foreign talent – including a delay in local players securing a first-team place and therefore vital experience – before dismissing them. As they put it: “Empirically, we have shown for the case of European basketball that any negatives appear to be dominated by the positive influence of foreign players.”

There was, though, a subsidiary finding from the basketball study that may be more soothing to traditional England supporters: winning youth titles in the preceding years is a very strong predictor of success at senior international level. As Forrest puts it: “If football is like basketball, then good times are indeed coming for England.”

Academics have also found that when players play abroad it improves the performance of the national team.

All this is not to suggest that there should not be some limits. Southgate needs his best youngsters to be playing regularly in the top leagues. No one disputes that such players need minutes to develop – something that is impossible to do when there is an established international ahead of them.

Facebook Twitter Pinterest Jadon Sancho breaks through the Czech Republic defence. Photograph: Shaun Brooks/Action Plus via Getty Images

Just ask Jadon Sancho, who left for Borussia Dortmund, or another of Manchester City’s wunderkinder, Phil Foden, who has played only 96 minutes in the Premier League this season.

It is understandable why some in the game are worried about this issue. After all, when the Premier League began in 1992 there were only 13 foreign players. Now almost every top club has more than that. However this has long been a debate too often hijacked by scaremongering or populist posturing.

The fact is when countries are looking for a bogeyman for the woes of their national team they should look within – not without.