I saw this puzzle on a pub wall in Whitby this week, the chap who set the puzzle passed away and his surviving relatives are not giving up the answer, the frame to the puzzle has a few words coming down but with no clues to their solution, the last letter in the 6 may be a U as the 3 word answer that comes there starts with a Q and unless it is QED or something like that then a U would be the obvious letter. It has bugged me for a good few days but I may well drop it very soon!!!