Looks like mostly a can response. Likely everyone who writes the Queen gets the same response. May not even read the letters except to get the names right.
That's government policy. If they get too many letters, they hire a minion, train them to imitate a lady-in-waiting's handwriting, and carry on. I'm amazed at how people are duped into thinking it's a personal response like this. And then they pass it on to their kids. Little wonder our planet remains ignorant on so many levels, if they can't see through this one.