Thank's Quisling. I resolved the problem in the end. I had missed the fact that something started with ?' and my potential 3rd item involved in the court case was actually the precursor to the entry in the grid. Somewhere along the line I'd forgotten that they had become magistrates! 😄
As others have said the theme was a little obscure - although the hidden message is supposed to have become an English
calque (a term I hadn't heard before, along with the expression). Wiki, as ever, proved to be and endgame essential!