After WW2 the fight for global supremacy was between the United States and the Soviet Union with the United Kingdom taking a step back. Why did they do that? Why didn't they just rebuild both their nation and their military and continue their role as the western superpower?
UK was in the lead for sometime as well. But its coffers were running dry, and to be honest the US bailed the UK out of two world wars already. UK really screwed up the endgame, ie Suez Crisis. No idea why Anthony Eden really messed it up.
US, not UK, was in a better position as well to spar with the Soviets, as it was Truman who partially started the whole Cold War Mess. Partially why there is an East West divide is because of Churchill and Truman. It was like a power vacumn in the capitalist world after WW2. France was in no position to be the leader, as CDG had a broken country on his hands. Atlee just got elected, so come on give him some time to adapt to the new country. Left was USA, who had the economic power to become the leader of the capitalist world, what we all call the West today, and USSR launched its own PR programme, ie Cominform and Warsaw Pact.