Surely some mistake !

HMRC complying with the law - that has to be some mistake.

They have proved time and time again that when it suits them they will ignore the law - even on points that have been dealt with (and they've lost) before. Imposing limits on "for personal use/consumption" and impounding vehicles for "smuggling" when people go on a "booze cruise" day trip to France. They done it many times, been taken to court and lost, and yet they still continued.