As my mail quoted in https://www.cl.cam.ac.uk/~mgk25/ucs/utf-8-history.txt says, Ken worked out a new packing that avoided all the problems with the existing ones. He didn't alter Prosser's encoding. UTF-8, as it was later called, was not based on anything but it was deeply informed by a couple of years of work coming to grips with the problem of programming with multibyte characters. What Prosser did do, and what we - all of us - are very grateful for, is start the conversation about replacing UTF with something practical.

(Speaking of design by committee, the multibyte stuff in C89 was atrocious, and I heard was done in committee to get someone, perhaps the Japanese, to sign off.)

Regarding windows, Nathan Myrhvold visited Bell Labs around this time, and we tried to talk to him about this, but he wasn't interested, claiming they had it all worked out. We later learned what he meant, and lamented. Not the only time someone wasn't open to hear an idea that might be worth hearing, but an educational one.

It's important historically to understand how all the forces came together that day. The world was ready for a solution to international text, the proposed character set was acceptable to most but the ASCII compatibility issues were unbearable, the proposed solution to that was noxious, various committees were starting to solve the problem in committee, leading to technical briefs of varying quality, none right, and somehow a phone call was made one afternoon to a couple of people who had been thinking and working these issues for ages, one of whom was a genius. And it all worked out, which is truly unusual.

-rob