▁made ▁her ▁debut ▁in ▁January ▁ 1 9 5 5 ▁as ▁the ▁" first ▁flower ▁girl " ▁in ▁Wagner ' s ▁Par s if al ▁at ▁the ▁Teatro ▁San ▁Carlo ▁in ▁Nap les , ▁Karl ▁B ö hm ▁conduct ing . ▁She ▁also ▁sang ▁in ▁Bas le ▁at ▁the ▁Teatro ▁San ▁Carlo . ▁On ▁ 1 7 ▁March ▁ 1 9 5 6 ▁she ▁made ▁her ▁debut ▁at ▁the ▁Vienna ▁State ▁Opera ▁as ▁the ▁Queen ▁of ▁the ▁Night ▁in ▁Die ▁Za uber fl ö te ▁by ▁Moz art ▁and ▁remained ▁with ▁the ▁Vienna ▁State ▁Opera ▁until ▁ 1 9 7 8 . ▁Her ▁Cov ent ▁Garden ▁debut ▁was ▁in ▁ 1 9 5 6 , ▁in ▁the ▁same ▁role . ▁ ▁Her ▁roles ▁were ▁limited ▁in ▁the ▁United ▁Kingdom ▁as ▁the ▁Equ ity ▁boy c ott ▁of ▁South ▁Africa ▁due ▁to ▁A part heid , ▁prevent ed ▁its ▁members ▁from ▁having ▁anything ▁to ▁do ▁with ▁South ▁Africa ' s ▁ ▁entertain ment ▁industry . ▁ ▁Co ert se ▁sang ▁the ▁sop rano ▁part ▁in ▁Bach ' s ▁Matth ä us - Pass ion ▁at ▁Fritz ▁W under lich ' s ▁first ▁appearance ▁in ▁Vienna ▁in ▁ 1 9 5 8 , ▁when ▁he ▁performed ▁the ▁ten or ▁a rias ▁with ▁Julius ▁P atz ak ▁singing ▁the ▁Evangel ist . ▁In ▁ 1 9 5 8 , ▁Co ert se ▁and ▁Fritz ▁W under lich ▁again ▁worked ▁together ▁at ▁the ▁A ix - en - Pro v ence ▁festival ▁in ▁Die ▁Za uber fl