First thing off the top of my head: get our GLAM contacts in order and ask them:
"We can't do political lobbying. But what can we do to help?"
It's reasonably clear that this is an ambit claim to see who kicks up a fuss - like when the BBC discovered people love 6 Music, and that their Asian Network demographic preferred 6 Music ;-)
So it strikes me as feasible that a fuss in the general name of the arts is reasonably within WMUK's charitable objectives and won't violate anyone's expectations of neutrality. It'll also be powerful signaling that Wikimedia are one of the few thoroughly Internet groups to actively work for the preservation of culture. (Much as, as Geni has noted, we're the only web 2.0 site to give a hoot about copyright.)
It will be worth remaining cognisant, of course, of the Iron Law of Institutions: we care about the collections themselves, the museum boards care about their power over the money per se and secondarily about what it's spent on.
But the first step remains: offer them our help and ask what we, as huge fans of museums and what they do, can do to help.
- d.