With a POD as World War II is winding down, have the British Empire continue its power and influence politically, financially, and militarily in the post war world even with the rise of American power and influence.
In this timeline the British Empire continues much as it was at its height in the mid 19th and early 20th Centuries, American power and influence still grows to what it became in the post war era and still is today.
There are two major superpowers the UK and the USA and they are the close allies they are today. The USSR never becomes the major superpower it did in our timeline. Yes there is still a major cold war much as we knew it and the USSR and the Eastern Block still constitute a major danger/threat, including the threat or fear of nuclear war with the west. But the USSR never becomes the great superpower that the UK and USA are.