Who were the allies of England during World War 2?
- Throughout the war: the Commonwealth countries including: Canada, Australia, New Zealand, South Africa, India - and others.
- In the early stages, also Poland and France. A little later also Norway, the Netherlands, then Greece, but these countries were defeated.
- From 1941 onwards also the Soviet Union and the US.
Not such an easy question:
Take France. An ally, through to the fall of France in May 1940. After that Vichy French forces were in some cases actively hostile (Syria, Madagascar, North Africa) and the French Navy was shelled by the British one (Oran, Mers-el-Kebir). And yet a French resistance movement and "Free French" forces, fielding whole divisions by the end of the war, were very much British allies.
The Soviet Union started WW2 allied to Germany, dividing Poland between them. It was only Germany turning on Russia in 1941 with operation Barbarossa which transformed the situation. This same shift moved Finland, which was in conflict with Russia, from a potential ally to an axis country without any change in position on their part.
Then there's the complexities of Yugoslavia: research "Chetniks" and "Prince Paul of Yugoslavia"
I think the question should be "Who were the Allies of the United Kingdom in World War II" as Scotland, Northern Ireland and Wales as the other constituent members of the UK were just as involved as England.
The United States, France, Canada, and Australia were allies with England.
England allied with the United States, France, the Soviet Union, nationalist China, Poland, Canada, Australia, New Zealand, South Africa, Belgium, the Netherlands, Greece, Yugoslavia, Norway, Brazil, Czechoslovakia, Ethiopia, India, Mexico, the Philippines, and Albania.