Lady Barrett was born in Henbury in Gloucestershire now part of Bristol, and she was the fourth child of merchant Benjamin Perry.

[1] She received little formal education in the early part of her life, she studied physiology and organic chemistry at University College, Bristol, and graduated with a first-class BSc in 1895.

[2] At the time of their marriage, Sir William, aged 72, was a former Professor of Physics at the Royal College of Science for Ireland in Dublin.

[5] In 1916, Barrett led a fund-raising campaign to extend the hospital, adding maternity, paediatric and infant welfare facilities.

[6] Barrett advocated for "state interference" in the sex lives of "the unfit" to implement birth control, because she believed that propaganda would be ineffective.