Having a discussion at home. What are the legalities of covering music if you are playing down the local boozer or something? My wife thinks you need permission, but I am not so sure. Maybe it is different in America.

I think it’s covered in the venues PPL/PRS license.

I Am Not A Music Lawyer

I think it’s covered in the venues PPL/PRS license.

I Am Not A Music Lawyer
I think this might be the case, if a band do any covers, the songs are noted and appropriate payment made.
Plenty of bands/artists drop covers into a set, so allowance has to be made for a cover or two just appearing that wasn’t on the setlist.
Joan Baez is a classic example; I’ve got at least one of her setlists where half the songs written down were never performed, others substituted, and a number of those that were, were covers, by Dylan or others she’d worked with, like Thea Gilmore.

In the UK, as long as you have not made an new arrangement of a song (changed any of the original song) and the venue has a PRS licence then you don’t need permission. The venue will report to the PRS that the song has been played and they will pay whomever owns the performance rights a royalty.