Born in Flagstaff Cottage, Lamorna (the eldest daughter of Samuel John Lamorna BIRCH and Houghton VIVIAN), she was often painted by the artists of the Newlyn colony and their visitors (such as Laura KNIGHT and Harold KNIGHT, Thomas Cooper GOTCH, Phil Whiting, etc). Mornie and her sister Joan both showed handicrafts, along with their mother, at the Newlyn Art Gallery in the 1920s and 30s, and both were to develop talents in watercolour and oils. Her beloved Lamorna featured regularly in her work, and she also specialised in flower painting. She was educated at Badminton School, Bristol, taking some classes at Bristol School of Art.

In 1939 Mornie and her husband Jimmy (James Lennox Kerr, the writer) returned to Cornwall from Scotland where they had settled, and where she had taken further art lessons in Paisley. Following her mother's death in 1944, she and Jimmy ran the family home of Flagstaff on the cliffs above Lamorna Cove, looking after her father there until his death in 1955. In later life, she focused on driftwood sculpture.

A friend to many artists of her father's circle, including a lifelong friendship with Laura KNIGHT, she exhibited regularly in mixed shows at Newlyn. Her first success at the Royal Academy was in 1939, and she continued to be hung there regularly throughout her father's life. She was Chairman of the NSA Council (1953-5), becoming Hon President following her father's death that same year. Despite subsequent diminished artistic success, Mornie was a hugely influential figure in the Lamorna valley who was considered an excellent teacher and enjoyed many close friendships.

Jimmy died in 1963, and she continued painting, setting up a teaching and painting circle which continued under her supervision until her death at Lamorna in 1990.

Their work was displayed annually at the Lamorna Village Hall, where the series continues to the present day.  An E L Kerr Archive is kept in the WCAA, gathered for a small Retrospective mounted at the Jamieson Library, Newmill by friends in 1990. Carn Gloose was exhibited at Penlee (2002), and Still life with Jug was sold in 2004 at the Queens Hotel, Penzance Auction for the WCAA Establishment Fund.

A biographical memoir, In Time & Place, Lamorna, was published in 1994 by her friend and pupil, Melissa Hardie, and is based upon her long life among the artists of the West Cornwall area.  It is largely abstracted within Artists in Newlyn & West Cornwall: Dictionary and sourcebook (2009). She is buried near her father and her friend Pog YGLESIAS in the burial ground at Paul.

Her son, the late Adam KERR, and his artist wife Judith KERR, kept the artistic traditions of Flagstaff Cottage, Lamorna alive for the area, with Adam serving as President of the Lamorna Society of Artists who work and exhibit together in the Valley.  Many of Mornie's former pupils are working today.