Churchill helped the Russians during the war even though he was a fervent opponent of communism. He wanted the allies to beat the Soviets to Berlin in the last months of the war to prevent them from occupying the city, but larger war aims prevented that action.
Churchill was voted out of office in 1945, after Germany's surrender and while he was attending the Postdam Conference in Germany. He was replaced by Clement Attlee. However, Churchill was again elected Prime Minister in 1951 and served until 1955. He died in 1965.