This particularly tricky theme will really get your nerves up, until you solve it. The revealer and title, FLIP THE BIRD, is a literal hint to the starred answers: there’s a bird within each answer ...

You report that the lead bird in the V-formation of northern bald ibises “often swaps places with the bird behind it” (7 February, p 16). But surely there are two birds behind it, on either side.

As Shakespeare would say, "much ado about nothing." Apparently, many people have obscenities in their heads and some people like to tut-tut about them. Hypocrites are always with us. It is ...