Otl, England, after constant ravaging by Danish invaders, norman invaders, norwegians, basically everyone, and the black death, had been rendered a rump state on the Danish Sea as Scotland and Wales expanded and eventually united, with the Celtic Kingdom of Britain absorbing England and Ireland, claiming all of Britain by 1480. Its navy rivaled by only Denmark, and wealth matched only by perhaps the low countries. Lothian has long been considered the Northern Rome, never once taken by a foreign power.
The CB, of course, went on to colonize Darien, eastern America, grab Brazil from the portuguese, Thailand and Cambodia, as well as almost all of east africa spare the French Cape and Danish Ethiopia.
But what if that didn't happen? What if one of those invasions is successful enough the population is replaced, or just never happened? Would England, of all nations, conquer the isles and create a true colonial empire? Or would Denmark simply run the seas as it's own personal bank?