Joan Smith: Mature protesters don't throw bricks, they cast a vote

They came together under the umbrella of the G20 summit and seem to have been good-natured for the most part, but the event was marred by the presence of masked protesters who smashed their way into a branch of the Royal Bank of Scotland. Windows were broken and slogans daubed on the walls of the bank, which has become a symbol of public anger towards financial institutions which have had to be propped up by vast injections of public money. On Wednesday evening, there were even more violent scenes in Strasbourg where protesters tried to barricade the streets ahead of the Nato summit. Clearly, public anger towards politicians and institutions isn't confined to the UK.

Two days later, it was reported that the former chief executive of RBS, Sir Fred Goodwin, might voluntarily relinquish some of his £703,000-a-year pension; last month, windows were smashed at Goodwin's Edinburgh home by a group which threatened further attacks on "criminal" bank bosses. Some have deplored the way in which the issue has been personalised, but they are fighting a lonely battle against the prevailing public mood.

There was little sympathy for Goodwin when his house was vandalised, and not much for staff at the besieged branch; it was even asked why the branch hadn't been boarded up, as though responsibility lay with management rather than the masked thugs who attacked it. It should be obvious that counter staff are not the enemy – their jobs are at risk along with everyone else's – and executives like Goodwin couldn't have got away with risky investments without the support of their boards and inaction from politicians who were too timid to regulate. Political leaders acknowledge there has been a collective failure of the financial system, which is why the G20 has turned itself into what is in effect the world's new finance committee.

Capitalism hasn't been overthrown and isn't likely to be, even if Gordon Brown's new moral version is an unknown quantity. But the violence in London and Strasbourg should ring alarm bells, reminding us that the public mood is poised between anger and vindictiveness. Long before the financial markets plunged into turmoil, the internet was encouraging a corrosive atmosphere of blame and cynicism, encouraging people to trade wild accusations under the cloak of anonymity. Now we are seeing masked protesters on British streets – it also happened three years ago when Islamists marched on the Danish embassy in London – and it's an incredibly ugly development.

Few of us are likely to start smashing up banks, but failing to condemn those who do is a first step in that direction. Being angry doesn't mean abandoning your moral compass, and anyone who blames the present government for the mess we're in can vote for another party at the next general election. This country is a democracy – the Iron Duke got his shutters but lost the argument – and there's absolutely no excuse for political violence.