He's still a mister. It's whether you buy in to "this is a male adult" vs. "I must respect this person's title because HM The Queen bestowed it on them".

Mr Berners-Lee surely won't feel offended because the person addressing him isn't a [UK] royalist?

Calling him Berners-Lee sounds like you would rather not use titles at all, which seems like a defensible position. Calling him Mr Berners-Lee sounds like you're going out of your way to deliberately use the wrong title, which just seems rude.

All adult males in the UK that you don't know the first name of but do know the surname of are called "Mr $Surname" as a social norm. Adjusting that designation because the Queen says so is very common too, but maintaining the status quo is just being apathetic towards the Queens edicts.

Most of her subjects do not complain. Some of them think we should have done away with such notions of reigning over other people already.

FWIW outside celebrity circles it is often considered quite gauche to insist on such pompous titles.

If you insist I'd be happy with calling him Professor Berners-Lee (even assuming he doesn't still have an active official professorship). If you want to talk about proper titles then is Sir Berners-Lee also rude when it should, by the right of HM EIIR be "Professor Sir Berners-Lee" [when spoken]?

If you're worried about recognition I think Mr Berners-Lee is not lacking in that department and was already party to the Queens inner circle as a holder of the Order of Merit which appears to be a far greater royal honour than a "mere" KBE. He has my utmost respect, if you doubted it.

That's not the case though, just as, more obviously, 'Mrs' isn't limited in meaning to 'this is a female adult'.

Increasingly and to the point of arguable totality, such titles are bestowed by popularity, committee, and HM Government. Damned shame, since it would mean more what it should were it not given to celebrity riff-raff for 'services to sport'.

I digress. You say it's fine as a non-'UK royalist' to use an improper title; I say I bet most of the world doesn't use even Mr, and I'd do my utmost to pay proper respect to local custom and any honours.

Does local custom work both ways? I think most Americans would consider "Mister" perfectly courteous.

I'm not sure what you mean by working both ways, I'm saying as the speaker one respects the subject's title, even if not 'recognised' natively.

For example, I'm not Catholic, but I would of course refer to Pope Francis; not 'Mr Francis', or anything involving his birth (as opposed to regnal) name.

I think the norm is the current surroundings, not wherever the subject is from. Dr. Smith is Smith-sensei in Japan. The New York Times is known for its use of courtesy titles, and it calls knights "Mr.".

Pope is a high office, and Francis is his chosen name. It would be rude of you to call him by his birth name; it would be rude of him to insist you call him "Your Holiness", although you probably should if you're visiting the Vatican.

Do you similarly never refer to people as Doctor, Reverend, Minister, or Coach so-and-so? It's part of his name. If Sir Tim didn't want to be knighted, I feel confident he wouldn't have been. You'll note that his wikipedia page calls him Sir Tim, and I feel confident he could change it if he so chose.

You are clearly free to call him whatever you want, but I would advise you to be honest enough to realize that you're projecting your feelings about royalists onto him, and not calling him what he has chosen to be called.

In practice you're right, i call people what they indicate their designation to be. Where I work we've had a person call themselves something like "Grand Wizard-Admiral of the Terran System" - some people like a pompous name.

If a person is an MD, professor, and such then that's totally acceptable. If the designation is "the Queen says you have to call me sir now" I don't really see what business it is of the Queen's or that it's more respectful to recognise a person because "the Queen smiled at them" than recognising their actual work/effort as fellowship of a learned society does.

It's an anachronous system of nepotism; bleurgh. What's not to like./s

Knighthood isn't a royalist issue. Australia has knighthoods bestowed by the prime minister. Unfortunately our PM decided to knight Prince Charles...

A knight of Her Britannic Majesty Queen Elizabeth the Second's Order of the British Empire. Yeah, nothing to do with royalty /s.

The could become a republic and everyone would be a knight of the president instead.