In the UK we belong to so many clubs! We are British sometimes, other times from our particular country. Exhibit A is the Tennis Player (
sometimes ) Andy Murray. When he is winning he's British and when he's losing he's Scottish!
It's vastly complicated and changes in a lifetime. When I was growing up ( the 60's ) England won the World Cup and everyone in the crowd had a Union Jack. Now, of course, it's the Cross of St George Flag. I'm not sold on it, to be honest as it feels a bit "invented".