Emily was the second child and first daughter of ten children of an independently wealthy flour & grains factor, Robert John Westrup and his wife Fanny. Her older brother was an architect, and the younger ones went into businesses at the managerial level. She was born in Hackney, London, Middlesex, and thereafter her family moved home to Hornsey, and then Stoke Newington.  One younger sister, Nellie Westrup (d 1916), became a prolific illustrator of children's books and her youngest sister, Ethel Kate WESTRUP became an artist and potter. Emily wrote nursery rhymes and stories for children, and also is known to have illustrated children's books, in the style of Kate Greenaway.  It is not yet known if she studied art or illustration, though she would have been well placed to do so, either at the Hornsey School of Art, or at Camberwell School of Art, where her later close friend Ella NAPER studied.

Her father died in 1903, and the family remaining at home removed to Fernhill Manor, New Milton, Hampshire. She and her artist sister Kate moved to Cornwall in about 1911 and established a home together at Lamorna.  They purchased the Lamorna Pottery which they ran together, Kate being the artist/potter, and Emily being the business manager and housekeeper. A partner in this business was Ella Naper who primarily made jewelry, some incorporating painting as well, and also painting on the ceramic products. 

Her writings include Doggy Doggerel being Nursery Rhymes for Doggy Times (1907, Blackie) and Doggy Doings (1914, Blackie and reprinted Dodge Publishing Company, New York c1940), both of which are illustrated by her sister Kate. Her own illustrations are in various publications and annuals, including This Train for Storyland (c1920, Cassell & Co)* where she is one of 8 named illustrators.

She and Kate were close friends with the Lamorna circle and participated in the artistic activities of the Valley and in Newlyn. Emily outlived her sister and remained in Lamorna until her death in her nineties. She is also listed as an exhibitor in the Craft section of the NAG show in 1926, but the item displayed is not recorded.