The Magic Circle is a club for magicians located in London, near Euston Train Station. For decades the club was considered, in the UK at least, to have a special place in the world of magic. If you were a magician the first question anyone would ask is whether you were in The Magic Circle. To a degree it also had international prestige, which they use to declare themselves an international club, even though the majority of their members are located within 50 miles of the London headquarters.
A massive change occurred in the club in the 90s, when due to a huge public campaign run by and on behalf of female magicians, the club accepted women for the first time. Yeah, in the progressive wonderland of 1991 they allowed female members. Conversely the International Brotherhood of Magicians has always been open to female members, since it was founded in 1922.
The actual shift in the club though was an after effect of the campaign to open The Magic Circle to women rather than the impact of the rule change itself.