Today, Parliament vote on Theresa May’s Brexit ‘plan B’ motion which she pitched roughly two weeks ago. With many questions still over what shape Brexit will take with less than two months left to go, here is the next part in an ongoing series about how we got here. In this blog, we’ll be looking at the rise of UKIP, the Lisbon Treaty and the promise by David Cameron to hold an in-out referendum on EU membership.

Breakthrough for the far-right (2004-2010)

Following on from their third place finish in the European elections, UKIP came won its first seats in the London Assembly (winning two seats) and came third in a by-election in Hartlepool, its best performance in a constituency election with over 10% of the vote and pushing the Conservative candidate into fourth place.

Also in 2004, the European Union was finalising the text for a constitution for the organisation. Prime Minister Tony Blair initially denied a need for a national referendum to approve of it, but later announced prior to the EU election that a vote would be held on its approval in 2005.

A bill to put the plans for the referendum into action was brought into Parliament in January 2005, with the proposed referendum question being “Should the United Kingdom approve the Treaty establishing a Constitution for the European Union?”. The proposed legislation suffered some criticism, with claims that measures to implement caps on campaign spending (up to £5 million) would not stop people from creating multiple groups to get around the spending limit. Moreover, there was anger among some that the Government would be able to publish information about its view up to a month before the vote with no spending limit.

However, plans for a referendum were later shelved following similar referenda in France and the Netherlands, which both voted against the proposed treaty. The cancellation of the referendum was seen as a broken promise by eurosceptics.

The general election in 2005 saw both UKIP and the British National Party (BNP) both marginally increased their share of the vote, with 2.2% and 0.7% respectively. UKIP’s result made them the fourth largest party in terms of vote share, whilst the BNP achieved a strong third place result in the constituency of Barking with 17% of the vote. This is the highest vote share a far-right party has achieved in a single constituency, with the party only a handful of votes away from beating the Conservative Party’s candidate.

The same year saw David Cameron, a Tory moderate, become leader of the Conservative Party. Cameron promised to lead the party out of the centre-right group in the European Parliament in a play to eurosceptics, but dismissed UKIP members in an interview on LBC as being mostly ‘fruitcakes, loonies and closet racists’.

In the years leading up to the following European election saw growing support for both UKIP and the BNP.

In 2006, UKIP elected Nigel Farage as leader of the party, having created an image of himself as being a ‘man of the people’ and a straight-talker telling things as they are. Under his leadership, he attempted to woo disillusioned Conservative voters disappointed with Cameron’s leadership with pledges to restore grammar schools, cut immigration and denying the scientific consensus on climate change. The same year saw the BNP make further gains in Barking and Dagenham, becoming the official opposition on the local council in that year’s local elections.

In 2007, with the EU Constitution being rejected by voters in France and the Netherlands, the European Commission proposed a replacement treaty Trying to capitalise on growing eurosceptic sentiment, and with Labour ruling out a referendum on the treaty, Cameron in 2007 gave a ‘cast iron guarantee’ of a referendum on the Lisbon Treaty. However, this promise was scrapped at the end of 2009.

With the main parties being rocked by the expenses scandal in 2009, UKIP increased their share of MEPs in the European elections, becoming the second largest party with 16.5% of the vote. In a shocking result, the BNP won its first (and only) seats in the European Parliament, marking the first time a far-right party had won representation in a national election in Britain. Andew Brons, elected alongside leader Nick Griffin as the party’s two MEPs, said on his election: “I regard this as the first step towards the United Kingdom… getting freedom from the European Union dictatorship”.

As the 2010 election approached, Nigel Farage stood down as leader of UKIP to contest the Speaker’s seat of Buckingham, with Malcolm Pearson taking up the post. In the campaign, Pearson tried to create a pact with other eurosceptic candidates in other parties and tried to get UKIP to stand down in seats where they were standing. He failed in this endeavour but still campaigned for eurosceptic Conservatives in the election.

Meanwhile, Nick Griffin of the BNP was invited onto the BBC’s flagship show Question Time in October 2009, in which Griffin’s performance was widely panned. His appearance on the show raised significant controversy, with criticism of the BBC for granting the far-right leader a platform on national television. Internal rifts emerged in the run up to the election after the party was forced to change its whites-only membership. Despite this, the party campaigned heavily in Barking to unseat Labour’s Margaret Hodge.

On the morning of election day itself, Nigel Farage was injured in a plane crash in Buckingham; the banner it was flying got caught in the plane’s stabiliser, forcing the nose of the plane down.

The election saw another record performance for both UKIP and the BNP, winning 3.1% and 1.9% of the vote respectively. Both parties, however, missed out on a seat in Parliament. Farage came third in the seat of Buckingham with 17%, and Griffin in Barking came a disappointing third, with the party actually losing votes in the seat. This would mark a turning point in the party’s fortune, with the BNP declining into irrelevance as it haemorrhaged votes to UKIP.

Cameron promises a referendum (2010-2015)

Farage returned as UKIP leader after the general election and the party saw growing success in a number of local elections and constituency by-elections, with the party coming second repeatedly in several of them. Their vote share in these constituencies jumped to new highs, reaching 21.7% in Rotherham in November 2012, and 27.8% in Eastleigh just three months later, where the party came within 2,000 votes of winning the seat from the Liberal Democrats, a coalition partner to the ruling Conservative Party. Around this point, the party overtook the Liberal Democrats in national polling.

In January 2013, Prime Minister David Cameron promised an in-out referendum on membership of the European Union, saying he would try to negotiate Britain’s relationship and then put that to a simple vote between staying with the new terms or leaving the EU. This faced criticism from other European countries, which said that Britain could not cherry pick what it wants from the organisation, and from the leader of the opposition Ed Miliband, who accused the Conservatives of running scared of UKIP. Miliband said that such a referendum risked ‘[putting] Britain through years of uncertainty and take a huge gamble with the economy’.

It has since been rumoured that Cameron did not expect to have to deliver on this promise, believing that a continuation of a coalition with the Liberal Democrats would be the likely outcome of the next election.

2014 marked a major breakthrough for UKIP. In that year’s European elections, UKIP won the most amount of votes and MEPs with a vote share of 27.5%; this was the first time in over 100 years that neither Labour or the Conservatives had won a national election. The party gained seats in all areas of the United Kingdom for the first time, with the exception of Northern Ireland. In the last three months of the year, the party also gained its first two MPs, with Douglas Carswell and Mark Reckless both defecting from the Conservatives. Both men chose to fight a by-election after moving to UKIP and won with 59.7% and 42.1% respectively.

With UKIP regularly polling at 15% or more and with a coalition government in power for the first time in many decades, it was thought that UKIP could potentially hold the balance of power at the next election and could prop up a Conservative-led government, with the Liberal Democrats warning of a ‘Blukip’ government. One poll suggested that the party could win up to 100 seats at the election in 2015. However, it was not to be.

UKIP was only able to hold onto its seat in Clacton, with Mark Reckless losing his seat and Nigel Farage again missing out on a seat in Parliament, this time in South Thanet. Farage came second to the Conservatives by less than 3,000 votes. It would later emerge that the Conservatives had overspent in campaigning in the constituency.

Despite this, the party massively increased its share of the vote to 12.5%, overtaking the Liberal Democrats to become the third largest party in terms of vote share. However, Nigel Farage chose to stand down as party leader, having promised to do so if he failed to win a seat of his own in Parliament He would soon return, however, after the party rejected his resignation, saying the campaign had been a ‘great success’.

Support for Farage from within the party began to dwindle later in the year after a disappointing result in a by-election in Oldham West and Royton, prompting some to suggest that the party needed a fresh face.

With the Conservatives now leading a majority government, the party brought a bill to Parliament near the end of 2015 to allow a referendum on Britain’s EU membership to take place.

What would follow would be one of the most divisive political campaigns in modern British political history.