Purists and lawyers, sit down. You may need smelling salts or whisky, according to taste. Ready? All right. I predict that your children, or perhaps your children’s children, will read in grammar textbooks that they is the third-person singular pronoun when referring to a person, as well as being the third-person plural pronoun. It will be confined to an animal or a thing.

Appalled? I admit to sharing some uneasiness about sentences such as ‘Each student may collect their course materials from the school office’. It could have been entirely plural, and avoided the seeming slide in number.