OTL Churchill is known as having an american mother, having a like of america itself and seeking to connect Britain more closely with the US, special relationship ect. However he was a great lover of the british empire, hardly the embodiment of american values.
In this timeline by the time Winston is an adult he has become an anti-american despite his mother's birthplace, everything american is to some degree tainted in his eye and finds american influence pernicious. Good anglo-american relations are to this Churchill pointless if not actually undesirable except in extraordinary circumstances.
To be clear the new Churchill is an anti american of the right-wing type, his criticisms are not anti-imperialist is nature.
So how does his life and career play out differently with this different attitude?