Great Britain, by far, was the power that suffered the most after World War II. It had taken the full force of the Luftwaffe, the German Air Force, during such spectacular moments as the Battle of Britain, and had come out galvanized as a people. France, however, did not have to suffer the same trauma though they were heavily bombarded by German forces.
What affected both countries after World War II was a rapid dissolution of their overseas empires. Again, Great Britain was greatly affected because they had the most to lose. This was something Prime Minister Winston Churchill was greatly grieved over because he was a staunch imperialist who had grown up during the heyday of the Victorian era. He did everything in his power to secure, at a minimum, controlling interests in the Middle East in order to maintain a firm grasp on such economic exports as oil. However, a surge in nationalism around the world, but particularly in India and Africa, led to the formation of independent governments where British and French governments relinquished control.
Though acclaimed internationally as a liberation movement of self-determination, the British and the French were severely crippled economically by these actions. But, as many historians have noted, both countries had little choice. As Winston Churchill observed, Britain was lucky to be in one piece and they owed the United States, and especially President Franklin Roosevelt, a great deal of thanks for their assistance.
An example of this "assistance" was the Lend-Lease Act, which swapped a number of obsolete destroyers for 99 year leases on certain British bases. The "special" relationship between Churchill and Roosevelt tilted the balance of power in Britain's favor on the continent and the eventual opening of a second front in eastern Europe by Joseph Stalin led to an even greater easing on Britain and France.