The third way à la Gandhi, civil disobedience; stand in the way between MPs and their local bar. If enough people refuse to work then there is only one solution left, change.
Civil disobedience in the US is either caged in "free speech areas", co-opted by undercover police, or totally ignored/denigrated by the media. The power wielders learned their lessons in the '60s and have worked on eliminated this issue since the '70s.
Well, GP's talking about the UK, not the US - but I suspect that if America really notices something happening, those Free Speech Zones will be relegated to the dustbin of history where they belong.