“The Premiership will suffer as a result because it has such a cosmopolitan flavour to it which makes it such attractive to viewers and sponsors,” Abt said. “As a product the best model is having international players playing alongside local and homegrown players.”

Polo may be affected with many Argentine players with European grandparents currently being able to play in the English season, from May to September, through the Bosman Ruling. "I don't think it will make any difference to the very top players, who are internationally recognised and are needed here to improve the sport in high-goal teams in the main tournaments. But it may affect lower handicap players - 2 or 3 goal players - from overseas using the same Ruling of European grandparents who are probably going to find it more difficult to come here," David Woodd, CEO of the Hurlingham Polo Association told The Daily Telegraph.

And what of London’s status as the sporting capital of Europe, if not the world? It is the go-to destination for major sporting championships and for American sports looking to expand their audience. Although the NFL declined to comment, Patsalos believes Brexit will endanger the current London international series of games. “The way the NFL view it is that London is a gateway to Europe,” Patsalos said. “My view is that (because) we pull out of Europe then they will reconsider that deal.”