History. The first international match was between Scotland and England. The UK is a country made up of 4K constituent countries, thus, for some sporting events, due to previous national organisations being formed, and inertia.

This is actually to their detriment, as there have been Welsh, Scottish and Northern Irish players that would have helped “the national team” but ended up in their home country’s team, like Gareth Bale or in the past, I think, George best.

It gets interesting with other sports, where N. Ireland joins with the all Ireland team.

Good news for you and Britain though, in the Olympics they compete as team GB. AFAIK the Scots contribute nicely with their curling prowess.