Following protests in Madrid which turned violent on Tuesday night, Giles Tremlett writes: Even before the march, government officials had loudly claimed that protesters were troublemakers from both the left and the right.

Perhaps that is why riot police felt they could hide their identity badges – a move that protesters say proves they feel themselves to be above the law. A startling example of police culture came in a tweet from José Manuel Sánchez of the Unified Police Union (SUP). “We support them not wearing badges for violent demonstrators,” he said during the demonstration. “Give it to them hard.” Television pictures of baton charges and rubber bullets suggest they did exactly that.

Organisers had said the attempt to ring the parliament building would be peaceful, but they also clearly expected arrests. Authorities said on Wednesday they had found 260kg of rocks that had been hurled at police – not indignado behaviour.

Opposition politicians warned the protest could not be ignored. “The country is slipping out of the government’s hands,” the socialist opposition leader Alfredo Pérez Rubalcaba said. “After yesterday’s demonstration it would be a mistake for politicians to talk only about public order.”

But while events in Madrid caught headlines, the settlement between Spaniards that has allowed them to enjoy almost four decades of democracy since the 1975 death of dictator General Francisco Franco was crumbling in a more serious fashion elsewhere.

In Barcelona it was legislators, not demonstrators, who were challenging the post-Franco settlement. Artur Mas, leader of the Catalan regional government called early elections for 25 November as politicians of all colours adapted to a game-changing demonstration for independence that brought hundreds of thousands of Catalans onto the city’s streets earlier this month.

Mas has called for Catalonia to have its own state. The upcoming elections will be seen as a plebiscite on that, however much his nationalist Convergence and Union coalition wraps itself in euphemisms and refuses to actually use the word “independence”. Once let out of its cage, the independence tiger may now prove impossible to put back – with polls showing a slim majority now in favour.