Tennis Rivalries

how come we have british athletes, tennis players & swimmers, but also english football, rugby, cricket teams?
why is it that we have england, scotland, ireland and wales football, rugby, cricket teams and british tennis players, athletes, rowers and cyclists to name? for me, it is either you support the UK as a whole in sport, and alas england, scotland, wales and northern ireland altogether or just as separate nations. likewise, what is it with the fierce rivalry between scotland and england? i just don’t understand why it happens to us and not with other countries. which would you go for and why?
If a sport isn’t popular enough to have a team for each country, we combine them to make a british team. It doesn’t automatically mean they hate each other if they play in separate teams. A bit of friendly rivalry is a good thing- like different houses for sports at school.
