Here’s what I think.
After the Brits tried unsuccessfully (twice) to bring the bleedin colonist back into the king’s fold, I think decided to change the locks.
You know, like parents do when kids run away or go off to college.
It’s like, “If they jolly don’t want to be a part of cheery England, hen we’re just going to speak a different bloody language so they won’t know what we’re saying. Right?!”
We’re the ones who still speak pre-revolutionary British English. They’re the ones who changed.
It’s like when your ex-wife drops 30 lbs, photoshops her pictures and tries to make it look like she’s having so much more fun without you.
That’s what the UK has been doing for 300 years. Making up new words and changing old ones is part of it.