In 1851, Procter became a Roman Catholic. She took much interest in social questions affecting women. She wrote the well-known songs Cleansing Fires and The Lost Chord, and among her many hymns are I do not ask, O Lord, that Life may be, and My God, I thank Thee who hast made.
She began to contribute to Household Words in 1853 and adopted the name of "Mary Berwick," so that editor Charles Dickens would not be prejudiced by his friendship for the Procters. Many of her poems were first published in Household Words and All the Year Round; afterward collected under the title of Legends and Lyrics, of which many editions appeared.
Her principal work is Legends and Lyrics, of which a first series, published in 1858, ran through nine editions in seven years, while a second series issued in 1860 met with a similar success. Her unambitious verses dealing with simple emotional themes in a simple manner have a charm which is scarcely explicable on the ground of high literary merit, but which is due rather to the fact that they are the cultured expression of an earnest and beneficent life.
Among the best known of her poems are "The Angel's Story," "The Legend of Bregenz," and "The Legend of Provence."