Leah-Marian was a company principal at the Royal Opera House, Covent Garden for eight years where she sang over thirty roles. She has subsequently sung for all the major British opera houses, Chatelet Opera, Paris and Angers Nantes Opera, France in roles ranging from the Title Role in Carmen, Maddalena in Rigoletto and Kabanicha in Kátya Kabanová to Flosshilde in Das Rheingold and Rossweise in Die Walküre. In concert she has appeared with international stars such as Bryn Terfel, the late Luciano Pavarotti and UK favourite, Lesley Garrett. In 2015 she performed the role of Genevieve in Pelléas et Mélisande for Welsh National Opera and Rossweisse in a concert performance of Act 3, Die Walküre as part of the 10th anniversary celebrations of the opening of the Wales Millennium Centre, Cardiff. This season, she returned to Scottish Opera to sing Jezibaba in Rusalka.