June 1949, Ferrier left for Amsterdam where, on 14 July, she sang in the world premiere of Britten's Spring Symphony, with Eduard van Beinum and the Concertgebouw Orchestra. Britten had written this work specifically for her. At the Edinburgh Festival in September she gave two recitals in which Bruno Walter acted as her piano accompanist. Ferrier felt that these recitals represented "a peak to which I had been groping for the last three years". A broadcast of one of the recitals was issued on record many years later; of this, the critic Alan Blyth wrote: "Walter's very personal and positive support obviously pushes Ferrier to give of her very best". The following 18 months saw almost uninterrupted activity, encompassing a number of visits to continental Europe and a third American tour between December 1949 and April 1950. This American trip broke new ground for Ferrier—the West Coast—and included three performances in San Francisco of Orfeo ed Euridice, with Pierre Monteux conducting. At the rehearsals Ferrier met the renowned American contralto Marian Anderson, who reportedly said of her English counterpart: "My God, what a voice—and what a face!" On Ferrier's return home the hectic pace continued, with a rapid succession of concerts in Amsterdam, London and Edinburgh followed by a tour of Austria, Switzerland and Italy. In Vienna, the soprano Elisabeth Schwarzkopf was Ferrier's co-soloist in a recorded performance of Bach's Mass in B minor, with the Vienna Symphony under Herbert von Karajan. Schwarzkopf later recalled Ferrier's singing of the Agnus Dei from the Mass as her highlight of the year. Early in 1951, while on tour in Rome, Ferrier learned of her father's death at the age of 83. Although she was upset by this news, she decided to continue with the tour; her diary entry for 30 January reads: "My Pappy died peacefully after flu and a slight stroke". She returned to London on 19 February, and was immediately busy rehearsing with Barbirolli and the Hallé a work that was new to her: Ernest Chausson's Poème de l'amour et de la mer. This was performed at Manchester on 28 February, to critical acclaim. Two weeks later Ferrier discovered a lump on her breast. She nevertheless fulfilled several engagements in Germany, the Netherlands and at Glyndebourne before seeing her doctor on 24 March. After tests at University College Hospital, cancer of the breast was diagnosed, and a mastectomy was performed