Although Great Britain is a national unit with regards to the Olympics, England, Northern Island, Scotland, and Wales are separate entities in FIFA. And at least two of the governing bodies want to maintain their grip on power:
England's successful march to the semi-finals of the European Under-21 championship in Holland means a British side is now entitled to one of the four places guaranteed by Uefa for European teams at the 2008 Olympics.
But because of a split between England and Northern Ireland and the rest of the British nations over the issue of an Olympic football team, the FA are to turn down the chance to enter a team in the under-23 tournament. It is understood that back in February they decided not to take up their right to enter the Beijing Games.
...Although England and Northern Ireland support the idea of fielding a British team in the Games, Scotland and Wales are opposed. They fear it would undermine the British nations' right to exist as four associations recognised by Fifa, world football's governing body.