SILVER-haired activists armed with a broom and a bucket quietly plastered posters on walls saying "Hola nou pais" - "Hello new country", as the last customers finished their drinks at pavement cafes on a warm October night.

That birth was exactly what they and many others were celebrating in Catalonia, a prosperous north-eastern region whose politicians voted in favour of independence from Spain on Friday.

The Spanish government was aghast, quickly triggering unprecedented constitutional measures to depose the regional government and take direct control of many of Catalonia's affairs in order to thwart secession.

Some independence-minded Catalans have vowed to carry out a wave of civil disobedience in response to the application of Article 155 of the Spanish Constitution, saying they refuse to recognise Madrid's authority.

A few days before the vote, Catalonia's foreign affairs minister, Raul Romeva, said he believed the region's civil servants, who number about 200,000, would continue following orders from "the elected and legitimate institutions" rather than from Madrid.

But secession is not a simple process.

A highly-disputed referendum on October 1 was declared illegal by Spain's constitutional court and boycotted by some Catalans who want to stay a part of Spain.

It was also marred by violence when national police brutally clashed with people determined to vote.

The desire for independence is not unanimous in Catalonia, which saw hundreds of thousands fill the streets on Sunday in favour of remaining in Spain, resulting in clashes with the police and pro-Spain protesters spotted giving Nazi salutes.

Exactly how Madrid imposes its authority on the region, and how independence-minded Catalan leaders and their supporters react, will be critical to how the drama plays out.

Since democracy was restored in Spain after dictator General Francisco Franco's death in 1975, Catalonia has run its own local institutions, including public media, schools, police, firefighters and health facilities.

Among the first to hint that Madrid's takeover would not go smoothly were Barcelona's firefighters.

Even before Article 155 was invoked, they issued a statement describing the central government's threats to do so as "the most serious attack suffered by Catalonia since 1939", the start of Franco's dictatorship.

"We do not recognise any other authority than our president, our government and our parliament," the statement said. "We will only obey the Catalan legality, which has all our legitimacy."

What this might translate into, however, is unclear. It is hardly likely that firefighters would refuse to extinguish blazes because of a political disagreement over who runs the fire department.

Marc Ferrer, a 43-year-old firefighter and spokesman for the Fire Brigade for Independence platform, said resistance would take a more symbolic form, with local services playing a "cat-and-mouse" game with Madrid.

"Even they don't know how to apply Article 155," he said. He refused to say what plans were being made for disobedience, citing security reasons.

"We are not going to do anything, we have never done anything, that puts people at risk," he stressed, adding that disobedience could mean refusing to display an official flag on the fire station or a Spanish insignia on fire trucks.

"The response from the Spanish state - the only thing they understand - is repression. For us, it's passive resistance and disobedience," Ferrer said.

"Now we will have to obey the minister. We won't do it, because we are convinced that our cause is just and noble."

But it is unclear how many civil servants would be willing to participate in general insubordination, particularly if they risk being fired.

One of the major civil servants' unions, the CSIF, rejected Romeva's call for civil disobedience as "irresponsible".

The union "considers that the vast majority of public employees in Catalonia will be on the side of the law", it said in a statement.

One key area is whether Madrid takes direct control of Catalonia's public media, as it has threatened.

"It's difficult to say what will happen, because we are regulated by parliamentary law," said Monica Terribas, a prominent Radio Catalan journalist and news presenter, noting that local media were producing balanced reporting on all issues.

"The public media in Catalonia are very professional," she said. "If they want to intervene in the editorial programmes, the professionals will not allow that."

Catalonia's three main public media outlets - TV3, Catalunya Radio and the ACN news agency - described Madrid's threat as "a direct attack on the citizens of Catalonia and a denial of the right to true, objective, pluralistic, balanced information, a fundamental right in any democracy".

Prime minister Mariano Rajoy has been at pains to point out he was not seeking to abolish Catalonia's self-governance, but rather to secure it by removing regional officials who had gone rogue and broken the law by declaring a new country.

He has called a regional election for December 21.

One of the most critical reactions could be from the region's police force, the Mossos d'Esquadra.

Spanish interior minister Juan Ignacio Zoido sent an open letter on Sunday to the police, calling for co-operation and unity.

"We are in a new era. And in this new scenario the Mossos d'Esquadra will once again be the police of all Catalans," he wrote.

Initial indications pointed to a relatively smooth transition of power.

Valentin Anadon, spokesman for the main regional police union FEPOL, which represents about 60% of the 17,000 members, was critical of Article 155 but said the police would always uphold the law.

Speaking before Madrid invoked the constitutional powers, Anadon hoped intervention into regional police would be "the least invasive possible."

But the idea that police might disobey orders was not something he saw happening.

"The police are there to comply with the laws. Disobedience might be an option for a politician ... but this is something that the members of the police have no room for manoeuvre in," he said.

"We are here to comply with the laws, period. The police of Catalonia must be the police of all Catalans," Anadon said.