There is one team from Wales, another from Northern Ireland and one from England. But no eleven was assembled under the colors of the United Kingdom.
This oddity is due to a very British vision where state and nation are two very separate entities. As proof, in 1884 the British organized an annual tournament in which teams from England, Wales, Scotland and Ireland (then united) participated. A bit as if the Bretons at home met Alsace…
For the British, state and nation are two different entities
Twenty years later, in 1904, the British imposed their conception of the nation on FIFA (founded the same year), drawing four teams from four parts of Great Britain. After the division of the island in 1921, Northern Ireland retains a national team under British guidance.
It is only at the Olympic Games that Great Britain, since 1894 and Pierre de Coubertin’s categorical refusal, has been forced to present a unified national team. But it’s called the team of… Great Britain!