Her career, encouraged by the conductor Sir Hamilton Harty, quickly developed, with breaks in the first years for vocal study in Milan.

During a long career, Baillie sang in complete recordings of Messiah, Elijah, Beethoven's Missa solemnis and Ninth Symphony.

She made her American debut in 1933 and between then and her retirement from the concert platform in the mid 1950s she sang in the US, New Zealand, the Far East and Africa as well as in Europe.

[5] In her spare time she sang at local concerts, at one of which in about 1913 she met Henry (Harry) Leonard Wrigley (1891–1957), a cotton trader.

In 1921 Hamilton Harty, conductor of the Hallé Orchestra, engaged her for several concerts, including performances of Haydn's The Creation and Handel's Messiah.

Her career quickly developed, but on Harty's advice she took a break from concert-giving in mid-1925 and another the following year to study in Milan with the vocal coach at La Scala, Gugliemo Somma.

[9] As The Times obituarist put it, for thirty years after her London debut "she was in constant demand on the concert platform, making a speciality of Messiah, The Creation, Elijah, and the choral work of Elgar".

[6] She made her American debut in 1933 at the Hollywood Bowl with Harty conducting; among the numbers she sang were "With verdure clad" from The Creation, an aria from Carmen and "Dove sono" from The Marriage of Figaro.

She sang at nineteen Three Choirs Festivals, beginning in 1929 at Worcester Cathedral, in Messiah, conducted by Sir Ivor Atkins.

Although she was known for her performances of British music, Kennedy comments that her repertory was "wider than was often supposed", including many works by Bach, Berlioz, Brahms, Dvořák, Kodály, Mendelssohn, Rachmaninoff "(The Bells as well as songs)", Schubert, Schumann, Richard Strauss, Szymanowski, Tchaikovsky and Hugo Wolf.

[1] After the war, Baillie made a second trip to New Zealand in 1948, returning home via the Far East, stopping in Singapore, Kuala Lumpur, and Penang, giving recitals in all of them.

[20] She sang in Honolulu in 1948,[21] and Washington National Cathedral the following year;[22] in 1953 she made a tour of southern Africa, giving recitals in cities including Nairobi, Salisbury, Johannesburg, Cape Town and Durban.