This is profoundly disappointing. A group of women meeting is suddenly taboo? Women talking? Discussions aren't dangerous. As has been said here, anyone could attend and if they have a sensible point to be made, it will be listened to, clearly. I think a lot of gc feminists would be happy to hear reasoned opinions from the other side - historically they've just been rather unforthcoming.
It's great the Quakers support LGBT rights - good for them. Do they really want to at the expense of women's rights? I don't know Brighton very well but the small amount of time I've spent there has given me the impression there are actually a high number of vulnerable women there - there are lots of drug users, lots of homeless people and masses of creative or hippie types who have experienced a lot of hardship (apologies if that offends anyone but it's just my experience of the city). The Quakers need to be supporting them, too.