The organising body of the Girl Guides says that trans girls - biological males - will have to leave by the 6th September to conform with a ruling by the Supreme Court last year. Whatever the perceived rights and wrongs of this decision, it's another chapter in the debate about whether we need single sex groups at all, from the Brownies to the gentleman's club.

We look into the history of the Girl Guides and the Scouts; hear what the law says about single sex organisations and ask whether girls really do better when boys aren't around?

Presenter: Adam Fleming