“There’s so much about sex in conventional relationships that’s so complicated, particularly heterosexual relationships,” Brown told me by phone last week. “I remember having this weird feeling with my first girlfriend, before we even had sex. Should I buy condoms just in case? If I bring them out will it look like I am over-planning?

“In prostitution there is no subtext. Everything is out there on the surface. We know what’s going to happen. There isn’t a mysterious part of the relationship, and there isn’t the same degree of shame around sex.”