Janet often stayed out for the evening; that was by no means an uncommon occurrence.

Art students are convivial souls; they love the unconventionality of the evenings in each other's company.
Sometimes Sally went with her to a small impromptu dance or a musical at-home in the purlieus of Chelsea.

But never before had she announced that she was going out by herself.

Mrs.Hewson did not profess to have any control over the morals of her lodgers, so long as they did not reflect in any way upon her own respectability; but she could not refrain from that British desire for interference in other people's affairs in the cause of morality itself.
Morality itself, not as any means to an end, but just its bare superficial display of conventional morals, is treasure in heaven to the average English mind.

And their morality itself is a poor business--cheap at the best.