Broadly, UKIP has so far had three ages in its 23-year history.

The first, lasting from its foundation in 1993 to its entry into the European Parliament in 1999, was its infancy. It slowly built its membership and activist base, experienced a bitter parting of the ways with Alan Sked, its founding leader, and first started to wrestle with the twin problems of appearing to be a ‘single issue party’ and having to rely entirely on voluntary donations.

The second age of UKIP began in June 1999 with the election of Nigel Farage, Jeffrey Titford and Michael Holmes as MEPs. The party could legitimately claim to have scored a surprise electoral success, and it now had a more reliable (if not always sufficient) financial and organisational basis thanks to the allowances secured from Brussels. It still wasn’t a peaceful time – Holmes was overthrown as leader a few months later, his successor served for just over two years, and there was the famous row with Kilroy-Silk, too – but it was a period of growth nonetheless. In 2004 they won ten more EP seats and saw their vote jump above 16 per cent nationally. The membership grew steadily, the cadre of experienced activists developed, new donors appeared and the twin messages of robust “common sense” and irreverent, alcohol-tinged heckling of mainstream politics grew into the popular consciousness – particularly in Farage’s first leadership stretch from 2006 to 2009. However, their progress was still slow – they only added 0.4 percentage points in the 2009 European elections and, with Lord Pearson as their well-intentioned but ineffective leader, their 2010 General Election share was just over double their 2001 total.

Arguably, the insurgent party’s third age began on the morning of General Election day 2010, when Farage’s plane crashed. The UKIP leader’s first two brushes with death – first in a car accident and then with cancer – had taught him, as a young man, to enjoy life. But the third left him re-assessing his mission – was he making the best use of his time? Was all the effort he’d expended on fighting the EU worth it? He has since spoken of how it made him “fearless”, and led him to resolve that he would give his absolute all to the campaign against the EU. It was a moment that would have a major impact on British history – by November he was back as UKIP leader, and proceeded from one success to another. By 2013, they were breaking through in the local elections, they won the 2014 European Election outright and picked up two MPs through defections, holding one in 2015. Their membership had more than doubled, and Farage himself had become the iconic image of his party, posing with a cigarette and a pint in pubs across the country. The referendum result was the victory he, and his colleagues, had been hoping for for more than 20 years.

Now, UKIP is embarking on a fourth age, triggered by Farage’s resignation as leader on Monday. The self-styled “People’s Army” has a big choice to make: what will its future look like? There is evidently a watchdog role, holding feet to the fire to ensure the Leave vote is honoured, but its members and would-be leaders hope for much more. Their message, their target voters, their objectives and, of course, their eventual fate will be decided by what happens next.

At the end of 2014, I wrote about the Five Tribes of UKIP, the competing factions and traditions within the party. It’s worth revisiting that now to see which of those is in the running to take over.

Bright Purple UKIP – the optimistic, broadly libertarian, subculture – still exists. Indeed, its principle champion, Douglas Carswell, is the entirety of the UKIP parliamentary party. But he is not going to stand, and Farage’s dislike for him has taken a deep root in the membership – he will fight on from his Clacton fortress, but he won’t be the next leader.

Grey UKIP and Blue UKIP, the traditional older, often ex-Tory core groups who played a major part in the party’s foundation and early years, have seen their influence recede as the ‘People’s Army’ has grown and changed. The closest they might have to a leadership candidate is Suzanne Evans, an ally of Carswell and former Conservative councillor. But her suspension, at the behest of the Faragistes, for six months looks likely to stand, preventing her from doing so. Neil Hamilton, now in the Welsh Assembly, is also a prominent voice from this tradition – he isn’t a feasible leadership candidate, but as a popular voice in the grassroots he may yet wield some influence.

So it’s left to the final two factions, the People’s Army tendency and Red UKIP, to decide the future of their party. As it happens, they have a lot in common. They are both fiercely anti-establishment, strongly anti-Conservative, deeply sceptical of big business and the leftist culture which dominates from quangos to the BBC.

The two traditions also point to very similar electoral strategies: where UKIP was once stereotyped as the party of retired colonels and disaffected Home Counties Tories, they instead argue that its natural voter is working class, on a low income and disillusioned with the economic and social direction of the country. In short, they are more likely to appear in a snobbish Emily Thornberry tweet about England flags than in a Farage-style covert coat.

That thinking is bolstered by the referendum result. While a majority of Conservatives voted Leave, Labour appear to offer the most vulnerable supporter base. Labour seat after Labour seat voted to Leave, and in the areas which did not it was often the supposedly safe Labour wards which formed the core of the Leave minority. Corbyn’s disastrous tenure as leader from the Hard Left tradition offers little to naturally small-c conservative working class voters, who already felt that their historic party had lost touch with their concerns – particularly on immigration.

Given that opportunity, it’s unsurprising that the more left-wing and more working class-focused tribes are at the front of the pack. The interesting question will be what mix of each ends up represented in UKIP’s leadership. The current favourites – Paul Nuttall and Steve Woolfe – are both from working class backgrounds in the North West, miles and years from Farage’s upbringing. Nuttall has over the years developed a robust message: heartily sceptical of sharia courts, vocally critical of political correctness, a supporter of the death penalty and a pro-life activist. Woolfe, a former City lawyer, is a somewhat less radical voice – he has been a strong immigration spokesman for his party, and an enthusiastic voice for lower taxes, but even when working alongside Patrick O’Flynn on the economics brief he never seemed comfortable with more headline-grabbing attacks on business and the free market. Each would mark a distinct new direction for their party.

The decision will be heavily influenced by a third man: Arron Banks. As the largest UKIP donor and the founder of Leave.EU, with its mailing lists and social media outlets, he sees a prominent role for himself in UKIP’s future. He has hinted that he might stand for leader (though given that he holds no elected office that would be an odd decision) but if he does not then he certainly has a chance to act as king-maker. Conveniently, only a few days before Farage’s departure he laid out a vision of “root and branch” reform, changing UKIP into a more online, bottom-up movement akin to Italy’s Five Star insurgency. He intends to get what he wants, regardless of the route – it would be an unwise leadership candidate who ignores his threat to set up “a whole new party” if UKIP does not prove to be the appropriate vehicle.

The question, then, is what kind of UKIP Banks would like. He is no leftist, and is unlikely to be a fan of any attempt to pursue the big-state nationalisation policies some on Red UKIP’s fringes have floated. Rather, he’s so People’s Army he’s practically wearing camouflage paint – a former Conservative, he prides himself on his denunciations of what he sees as self-interested, untrustworthy and posh Tories, and also on his gut feelings about what “real people” think and like. He isn’t particularly strategic in his campaigning, but he feels he can afford to rely on his instincts and whims to guide him to an effective platform – they regularly get him into bother, which he shrugs off as irrelevant media fuss, but they’re certainly popular among a sizeable minority of the electorate.

Whether UKIP can prosper with that approach remains to be seen, as does how far it can take them, but Banks means to find out. The figurehead could be Nuttall or Woolfe – or a less prominent figure if they don’t fit the bill. Whoever the new leader may be, if they want to differ from that line they may have trouble changing it.