Pod: 1775 goes differently, by 1980 (otl) the Anglo population is around 150 million, as Britain is part Europe, and the core parts of the empire, the British Empire would be the largest European nation-state.
This state would be a mix of Protestant denominations, Anglican, Presbyterian, Methodist and Congregations. A large Catholic population.
There would be about 60 million people in the British Isles, there would be less than 200 million people in British America and around 20 million people in British Australasia.
The big languages would be English, with many diverse dialects, American Southern, Scottish and Australian. Quebecois French, German.
It would be the most geographically diverse country, yet a very coherent national identity.