However, in a separate “Soft Power 30” ranking released one month previously by global consultancy Portland Communications, the UK was considered to be top for impact, followed by France, Germany and then the US.

HEPI’s new ranking considers just prime ministers, presidents and reigning monarchs in countries that are members or observers of the United Nations.

France was in a significantly stronger third position in this year’s HEPI profiling.

Nick Hillman, director of HEPI, used the US’s move into top spot to call for improved migration policy in the UK.

“In the past, we have been more successful than any other country in attracting the world’s future leaders. But these new figures suggest our position could be slipping,” he said.

“To ensure this does not become a long-term trend, we need to adopt a bold educational exports strategy, remove students from the main migration target and roll out the red carpet when people come to study here.”

HEPI did not consider people who studied as distance learners because soft power benefits are likely to be lower.

The presidents of Ethiopia and Rwanda and the president-elect of Zimbabwe completed UK qualifications via correspondence, noted the research – underlining wider benefits of British education qualifications exports.

Meanwhile, the report produced by Portland was based on respondents all around the world asked to rate countries based on seven different categories including culture, cuisine, and foreign policy.