Who is Beppe Grillo and what is Five Star Movement? All you need to know about the biggest threat to Italy's status quo

Italian Prime Minister Matteo Renzi has resigned and taken full responsibility for his “extraordinarily clear defeat” after the “No” campaign won a resounding victory in Sunday’s referendum.

The “No” win was even greater than opinion polls had previously indicated, presenting a major victory to the Five Star Movement, the driving force behind the campaign, which presented the referendum as a protest vote against Mr Renzi's status quo.

Having steadily grown since 2009 to become one of the most voted-for parties in Italy, and now heralded this major victory, the movement against Italy’s constitutional politics can no longer be overlooked in Italian politics.

So what is the Five Party Movement and who are the driving forces behind it?

Giuseppe Peiro Grillo, also known as 'Beppe', co-founded the movement in 2009. He studied as an accountant but did not finish university, instead failing into comedy, which in turn – along with his influential blog - helped him establish his political views and communicate them to a wide audience.

After being picked up by Italian TV presenter Pippo Baudo for his potential as a comedian not long after finishing school, Mr Grillo starred in a number of shows. He began to make a name for himself in the political sphere during the Eighties when he adopted political satire that offended some politicians.

In 1987, Mr Grillo was banished from publicly owned television after he offended the Italian Socialist Party and its leader Bettino Craxi, the then prime minister. Since the early Nineties his appearances on TV have become rare – thought to be because of the offence he causes Italian politicians.

But in 2014, the comedian and activist returned to public television to participate in the popular late-night political debate talk show Porta a Porta as part of his campaign for the 2014 European Parliament election - a show that attracted three million viewers and helped the movement build a name for itself.

Mr Grillo, now 68, is also an avid blogger and maintains a site in three different languages which reportedly ranks among the 10 most visited in the world and is considered one of the most influential.

As his political activism grew, he began to placed emphasis on the role of the Internet as a way to herald pathways to direct democracy and a fairer society, making him one of the leading champions of digital utopianism in Italy.

In 2005, Grillo used money donated by readers of his blog to buy a full-page advertisement in Italian newspaper La Repubblica, calling for the resignation of the then governor Antonio Fazio after the Antonveneta banking scandal. He was subsequently chosen as one of Time’s “European Heroes 2005” for targeting corruption and financial scandals.

Later the same year, Mr Grillo bought a page in the International Herald Tribune, saying that members of the Italian Parliament ought not to represent citizens if they have been convicted of a crime, even in the first degree of the three available in the Italian system.

In 2007, Grillo was permitted to speak to the members of the European Parliament in Brussels, where he drew attention to the state of Italian politics.

In May 2016 Grillo provoked criticism when he asked when the Mayor of London Sadiq Khan will “blow up Westminster” following his success in the mayoral election.

He has also declared his liking for Nigel Farage, appeared to compare migrants to rats and has been found to own a motor yacht and a Ferrari despite claiming to be an environmentalist - as well as speaking out in support of Dinald Trump.

Mr Grillo started the Five Star Movement - or Movimento 5 Stelle (M5s) along with web strategist and editor of his blog, Gianroberto Casaleggio, who died in April 2016.

In 2009 Mr Grillo and Mr Casaleggio used the blog and social networking site Meetup.com to bring people together to campaign on local issues and then field candidates for elections and since then it has risen to become one of the most voted-for parties in Italy.

The movement has at its heart been a reaction against Italy’s self-serving and corrupt politics, with a founding aim has been to cut parliamentarians’ salaries (the highest in Europe) by 80 per cent and to ensure financial accounts of all state bodies are accessible to the public.

Its policies have always been an eclectic mix of the anti-establishment, environmentalist, anti-globalist and eurosceptic, and its supporters have always come from across the political spetrum.

At the 2013 general election, the M5s came from nowhere to become the second most voted for party. Through ups and downs, its poll ratings have stood at around 30 per cent ever since, generally ahead of the centre right and only just behind the centre-left Democratic Party.

Despite several outcries such as the chaotic manner in which Virginia Raggi, the recently elected mayor of Rome, has been running her administration and allegations of activists being involved in falsifying signatures on the nomination papers of candidates for elections, the movement has gained momentum over recent years.

The M5s made a sensational debut in the parliamentary elections of 2013, surprising many political watchers when it won around 25 percent of the vote.

People generally support the party because it represents something different from a political class in whom vast swathes of the electorate have virtually no confidence.

The profile of M5s activists and supporters casts doubt on whether it would be able to govern effectively if it did win an election.

A vote for the M5s is a straightforward protest vote. Despite being united in their desire to shake up the status quo, M5s activists and supporters are divided across the whole range of issues separating left and right. They don’t necessarily share a position on the EU, taxation or migration – in fact M5s voters are more or less split down the middle.

It is therefore doubtful that such a party can remain cohesive when faced with the pressures of governing. The M5s would probably crumble under the weight of the responsibility for making choices that can only benefit some while hurting others.

Many members and supporters have left because they came into conflict with pressures to behave as mere party delegates, rather than as representatives, exercising their own judgement.

Mr Grillo - despite claiming to espouse the ideology of “bottom-up” democracy - has often sought to impose party discipline from the top down, dealing with rebels by threatening to withdraw their right to use the movement’s brand, of which he is the exclusive owner.