The ad would have annoyed me too, had I seen it.
However, I don't generally have a problem with the singular "they/their" to refer to a single person of unspecified gender. We can no longer use 'he'/'his' as used to be the norm, and saying 'he or she' / 'his or her' has now become old fashioned, not to mention clumsy if repeated. Nor can we use 'it' for a person, with the exception perhaps of an unborn or new-born baby.
Yes, we can often re-word a sentence to avoid the problem, but we shouldn't really need to go to such lengths, should we?
'They' serves the purpose very well, although it's worth noting that its use in this wayis nothing new. Many famous authors throughout history have used it and apparently it is even widely used in many versions of the Bible, including the King James version.
So why does the advert bother me, you are probably wondering. Well, I have to admit that I don't really know! I guess I must be guilty of double standards, expecting one thing from us ordinary people and something else from so-called experts. 
Why doesn't Starmer hold another referendum?
Retirement is it what you thought it would be?



