So what happens next? After the dust settles from Sunday's elections, widely forecast to return a pro-independence majority to the regional parliament, where does Catalonia go?

Angels Folch, a national co-ordinator of the hugely effective Assemblea Nacional Catalana (ANC), the grassroots association that organised September's 1.5 million-strong independence march, is fairly sure how things will pan out.

"We are confident of the outcome – independence," says Folch, a retired primary school teacher. "We have talked at length and in detail with all the main political parties in the regional parliament except the People's party [of the Spanish prime minister, Mariano Rajoy], which refused.

"And we are certain that those who dissolved the last parliament are absolutely sincere in their intention to give Catalonian citizens the right to vote and determine their own future. They will see this through."

Quite how the process advances will depend in large part on how Spain reacts, Folch says. "Madrid will not just say: 'You cannot vote.' It will try everything in its power to prevent it. So it may be that the Catalan parliament will have to take its responsibilities."

Folch believes the new parliament could have the legitimacy to declare independence as it stands, since two-thirds of the parties set to be elected are standing on platforms pledging support for self-determination. But if not, parliament can be dissolved again and new elections called on the explicit issue of independence.

"Then that new parliament will vote and declare independence," Folch says. "There would probably also be a follow-up referendum, a plebiscite, maybe two or three years later, allowing the people to say that yes, this is what they wanted."

The timetable for all this is quite confined. "It cannot take too long," Folch says. "It will have to be done step by step, but it must happen fast – I think within the next 24 months. And once it has started it cannot stop."

Her confidence is not based on nothing. The ANC, formally launchedin March, is the end-product of an impressive grassroots campaign born of a dawning conviction, since the mid-1990s, that "the idea that Spain is a true federal democracy, in which all the nationalities' rights are respected, is a joke.

"It's actually a democratic facade hiding a fundamentally imperialist structure. There is no real Spanish state – there are a series of nations that Castile conquered, and called Spain."

During the mid-2000s, as the Catalan parliament ratified a new regional constitution approved by popular plebiscite and then saw the Spanish constitutional court emasculate it, "more and more people began to realise we were not as autonomous as we thought. That this is something that goes really very deep, and that we are not, as Spain likes to suggest, mere circumstantial independentistas, driven by economic issues."

An early civil association to form at this time was called Platform for the Right to Decide. "The first group to really make the people's right to decide the number one priority," she says. That resulted in a major protest march through Brussels by some 5,000 Catalans in 2009.

Another group, Act of Sovereignty, symbolically buried the now defunct regional constitution with full ceremony in central Barcelona in 2010, and upped the political ante by sending letters to every party in the regional parliament demanding they take a public stand on the right to decide.

Starting in 2009, towns and villages around Catalonia – about 300 in all – started organising informal referendums on independence, culminating in Barcelona. That led to the formation of local politicians alliance the Association of Municipalities for Independence.

"All this began to create a real momentum, a real, snowballing movement on the streets," says Folch. "People felt less and less afraid of calling for independence. The pressure began to mount. And we who were members of these organisations realised we now had to take things further."

So the ANC was formed, "to make the Catalan nation visible in the streets; to grow the number of people who agree we want to be a nation; to unite people, not organisations or political parties; and to work for one single objective: a Catalan state."

The organisation, which has more than 30,000 active and paying individual members, is resolutely non-party political: its founding charter states that it can never become a political party, and that none of its leaders can hold positions of responsibility in political parties.

"Behind it all was also the realisation that the politicians would never take the plunge for self-determination unless they realised that there was a huge mass of people behind them – until they realise they will not lose any votes by backing this process," Folch says.

"In fact, far from being in trouble if they do support independence, they'll be in trouble if they don't." The result, after two years of planning, was last September's independence march: nearly 20% of Catalonia's population on the street, calling for the right to decide – and a parliament that may, finally, be willing to take the plunge.