^Just a word about the wider context and our thinking on this as well.
We try as an organisation to campaign on serious issues like miscarriage, SN and sexual violence. In order to be in any way effective on things like that, we need to engage with politicians, great and small. That's just not going to happen if MN is perceived as a place where posters can make enormously insulting statements about named public figures at will.
We also regularly get major politicians on for webchats - another thing that could just stop happening if we don't draw some lines about what we think isn't OK.
We realise some of you would rather be able to say whatever you like about Cameron/Miliband/Clegg/whoever, and just ditch the campaigns (and the webchats) - but that's not our position and not, we think, the position of MNers as a whole, given the enormous number of requests we get from users for both things.^
Rowan Well, you don't let people say gratuitously offensive things, do you? And if a politician declines an invitation because they do not like the tenor of Mumsnet debate then you can say so, or simply state that they were invited and they declined. Any politician refusing to support such important campaigns because they are not happy with what some posters in your forums say, as opposed to what your own editorial content says, really isn't cut out for British politics - a notoriously rough old game.