It's partly the story that makes Peter Maxwell Davies's last music-theatre piece, Mr Emmet Takes a Walk, so much more coherent and better structured than his first, Eight Songs for a Mad King. Mr Emmet is ticking off items on a "must-do" list before beheading himself under a train, whereas Mad King George is doing nothing in particular except rave on to the birds (represented by musical instruments) and show off a remarkable vocal range.