 Although the chorus and orchestra of Welsh National Opera have appeared on many commercial recordings , often featuring regular WNO soloists , there have been few sets , either audio or video , of the company 's own productions . Among those are Tristan und Isolde conducted by Goodall ( 1981 ) , <unk> et <unk> conducted by Boulez ( 1992 ) , The <unk> of the Guard , conducted by Mackerras ( 1995 ) , The Doctor of <unk> conducted by Armstrong ( 1998 ) , and <unk> conducted by Ivor Bolton , directed by David Alden ( 1999 ) . The BBC made a studio video recording of a WNO cast in <unk> <unk> , conducted by Armstrong in 1982 . 
