This autumn English National Opera is exploring the Orpheus myth by presenting four operatic takes on it. Now, following Gluck’s Orpheus and Eurydice and Offenbach’s Orpheus in the Underworld, both of which still have performances that can be seen, comes the third addition to the mix, Harrison Birtwistle’s The Mask of Orpheus. Without a doubt there is no other opera quite like it with the orchestra containing no strings, the score including electronic music (which was...