It’s ASB. Britain had an empire with global commitments, and massive strategic economic investments even where it didn’t outright own the land, Persia and China being just two examples. It needed good relations with strong friendly powers because it simple could no longer afford rivalry, the same reason that they’d entered into an entente with the French with in the first place. If they couldn’t come to some relationship with its old friends it would never muster the strength to see of the rising new rivals. In short, when you own a quarter of the world you really cannot be disengaged.