"Albion" was a name invented by people who did not live in the British isles. It refers possibly to the white cliffs of Dover ("Album" in Latin means "white"), as seen 20 miles away from the coast of France.
Celts and Ancient Britons inhabited the British Isles before the Roman invasion in AD 43. The Romans called it "Britannia", possibly after a local tribe in the British Isles. Since then, the population has been mixed, with further invasions by Saxons, and Angles, and Jutes, and Vikings, and Normans, etc.
Napoleon, just over 200 years ago, used the expression "Perfidious Albion".