In an interview back in April, UK Liberal Democrat leader Nick Clegg warned: "There is a danger in having any government of whatever composition led by a party which doesn't have a proper mandate across the country trying to push through really difficult decisions. I think a lot of people will react badly to that. [...] I think there's a very serious risk [of rioting in the streets]."
The irony is (for those not following UK politics) that, having joined a coalition government led by the Conservatives which is now pushing through major budget cuts (though not upholding existing tax laws, which would reduce the need for such slash and burn), Clegg is facing a personal backlash for breaking pledges he signed during the campaign not to raise university tuition fees.
I disagree with his implication that a coalition government does not have a proper mandate. That comment was simply playing to UK ignorance of the plethora of countries that have been more or less successfully governed by formal coalitions and the fact that all major political parties (including quite obviously his own) in every functioning democracy are de facto coalitions between various factions.
Will the UK see further mass protest against the current round of budget cuts? I think it is currently fairly likely. Whether or not these turn violent will depend on the precise mix of deliberate troublemakers (including possible agents provocateurs), abusive police tactics and a bloodthirsty media egging on both sides. Direct non-violent action is much more effective, but can be all-too-easily hijacked.