British Gas's programmers don't believe that a surname can be only a single character.
Their customer service agents worked around this by adding a parenthetical note to my record.
The result is hilarious postal mail that tries to reassure me that my surname really is what it is:
EDIT: Well this blew up. FAQ etc. at https://danq.me/it-is-only-q
@dan I had a friend whose first names were "A Gustav" which resulted him being unable to fly at least one airline that rejected single letter first names. EDIT: And of course, they would deny boarding if the name on the ticket wouldn't match his passport.
@oliof I get this kind of thing a LOT, but I've learned the workarounds now. For example, a problem I have when returning to the UK (although strangely never while abroad) is that the electronic passport gates at Border Control won't let me in. With a bit of social engineering I've worked out that it's my name that causes trouble with their computer systems, but it was annoying to have to try the gates three times before being rejected and sent to the queue-for-people-who-can't-use-the-gates.
So now I just go straight to that queue. Sometimes people try to stop me, and say "British passport? You need to go that way." To which I answer "I've been told to join that queue." Which is only a white lie: I WAS told to join that queue... on a previous visit to this airport. I know it's the fastest way through for me, now. I don't want to hold up the electronic gate queues when I know for a fact they're not going to work anyway.
Of course, by the time you turn up at the speak-to-a-human desk at border control for your own country, the human there immediately assumes there must be SOMETHING wrong with you (or else why would they have to deal with you, when they normally only have to deal with complicated edge cases). So I inevitably get lots of questions. I've gotten pretty good at pre-empting them, now, too, and just give a spiel as I arrive and hand my passport over that gets me through as fast as possible.
But yeah: I've never for a moment had any trouble with my name in any country other than the one I was born in and live in.