Irwin was born in
Highgate Hill, London to Andrew Clarke Irwin (a native of Perth, Western Australia, d. 1902) and Anna Julia Irwin (née Baker, d. 1899), the daughter of Col. George Baker of the 16th (Queens) Lancers. She was brought up by her uncle S. T. Irwin (Sidney Thomas Irwin), a master of Classics at
Clifton College, then a boys' school. Irwin attended the nearby
Clifton High School, a girls' school, in Bristol, after her parents died. She was educated at Clifton and at
Oxford University, where she took a degree in English. ==Career==