I think you will find it will be covered by online documentation where you declare it is for use not for sale. The paper process was in use even while we were in the EC. Certainly in 1985/6 I had to drive to Birmingham to get the document. Called a carnet. Everything has to be documented. Norway and Switzerland know this, and it is a pain. Serial numbers, descriptions, etc, etc.

I have been cracking-on about the return of needing a carnet ever since the referendum result was in. In this parish and in print in my columns in magazines.

And without the documentation you will be hit with import duty on return to the UK.

There will be other things crawling out of the woodwork. Income tax? The Rolling Stones used to (still?) specify they were met with a tax expert at the border!

There - not a mention of the "B" word.

(Oh and if you buy a guitar abroad, be sure to insist on a well used guitar case). Take an empty one with you?