Sorry, I have been so busy that I forgot to post this earlier. If you missed Saturday's (21/04/12) broadcast of Siegfried from the MET then you can still catch it at a number of sources. Might I recommend, if you have been unable to track it down, listening over at RTE Lyric FM on their on-demand player? It is difficult to know how long it will remain available with MET broadcasts but I would suspect at least for the next 5 days or so.
Give it a few moments and the broadcast should start. Any difficulties please let me know. If you have a pop-up blocker you may need to disable it for second or simply allow this one link
