Brexit this week has been all about the “backstop”, and whether the backstop needs a backstop, though no one yet has suggested the elegant solution of giving the second backstop its own backstop, and so on to an infinite series of backstops, the contemplation of which will unite the UK and EU in awestruck comity. But what, pray, is a backstop?

The term comes from cricket: from 1819 you could say “back-stop” instead of “long-stop” for a fielder placed behind the wicketkeeper to stop the ball at the back. From there the term spread to baseball, and then shooting: a backstop was a pile of earth behind the target to stop stray bullets, of the kind hardline Brexiters wouldn’t mind seeing flying anew. The Irish backstop, too, is a safety mechanism: as the UK agreed last December, if all else fails Northern Ireland must “maintain full alignment” with the single market and customs union to avoid a hard border.

Happily, backstop is also a transitive verb, meaning “to support, back up; to supply with necessary additional resources” (OED). Theresa May’s problem is that she is backstopped in parliament by the DUP, but they are opposed to the backstop. Perhaps it’s time to take a step back, and stop?