They had decidedly middle class values, and wanted to save the women (at least during the Victorian era). They thought the prostitutes were lost souls who had been chewed up by a patriarchal society. This was certainly true in some cases, but not in all. A lot of the prostitutes saw their work as an alternative to the horrible conditions of the dehumanizing industrial machine. I wish I could quote the relevant passages, but I'm on mobile. The monograph I am drawing from is the landmark work Prostitution and Victorian Society: Women, Class, and the State by Judith Walkowitz.

Laura Agustin sums it up well, in that mid 19th century utopianism and the rise in agency of middle class women meant that there was a boom in charitable organisations, in order to provide a fulfilling professional life for women. Temperance, poverty and an obsession with prostitution and 'fallen women' were at the forefront of these organisations concerns. It is widely accepted that the suffragette movement grew out of women's temperance, but that is largely shorthand in that the 'temperance' net was cast a lot wider than just alcohol.

Agustin goes as far as to argue that the template for the career prostitute was largely invented by these organisations. The little spoken reality of the sex industry is that most sex workers are transient. A number of factors dictate a career. Immediate financial needs, financial goals, beauty, relative youth, relationships, other employment. Sex workers tend to pass through the industry relatively quickly, and for most, it is an expedience, rather than a lifestyle. It was rare to find a woman on the streets of London that didn't work daylight hours in a factory. But by creating a narrative of fallen women and entrapment, charitable societies may have reinforced the stigmatisation of sex work and made it a lot more difficult to transition. That is Agustin in a nutshell.