Size eventually worked her way up to become the Lady Superintendent at
Liverpool Prison in 1925, where she "took with her an ethos developed in the reformatory borstal system." By the 1920s, the introduction of fines in lieu of short prison sentences in combination with the introduction of old age pensions led to a significant decrease in the female prison population, in particular those serving short sentences. Around May 1927, Size was appointed Deputy Governor at
Holloway Prison (which had become a women's only prison in 1902) and was the first woman to hold the post and the only woman in the UK to hold an equivalent role. By 1934, Holloway was the largest women's prison in the UK, holding 370 women prisoners out of a total population of about 800 women prisoners across all UK prisons. While Deputy Governor at Holloway, Size introduced a whole range of important reforms including considerable improvements in routine and in methods of classification at the prison. She also persuaded
Gracie Fields to perform at the prison for the prisoners. This reform programme of women's prisons in England in the late 1920s and into the 1930s brought about educational improvements and a new stress on the importance of femininity with mirrors being allowed in cells, more feminine wall colours, and allowing female inmates to purchase cosmetics and make-up. Other reforms put in place by Size included the converting an exercise yard at Holloway into a rose garden, where female prisoners could be trained in gardening - a skill which could be put to use in domestic service after their release from prison. More generally, Size developed handicrafts, modernised uniforms, established a canteen, introduced gardening and evening classes. Size served as Deputy Governor at Holloway Prison until 1941; both staff and prisoners were evacuated to Aylesbury Prison at the outbreak of the
Second World War. Between 1941 and 1942, Size was Governor of Aylesbury Prison, where Size arranged for prisoners to knit comforts for men and women which were sent to the
Red Cross Depot at
Oxford for distribution. == Askham Grange open prison, 1946-1952 ==