The Liberal Democrats will stand at the next general election on a platform of derailing Brexit and keeping Britain in the European Union, the party has announced.

Leader Tim Farron said on Saturday night that he would be “clear and unequivocal” with voters that if elected it would set aside the referendum result and keep Britain in the EU.

He said the referendum result amounted to a “howl of anger” at politicians and that the election of a liberal government would be a way of registering a change of heart by the electorate

Though the next general election is scheduled for 2020 under the Fixed Term Parliament Act (FTPA), David Cameron’s resignation and major loopholes in the legislation mean it could come as early as the autumn or early next year.

A successor to Mr Cameron is planned to be in place by Conservative Party conference in October and it is expected that whoever is chosen will immediately come under pressure to call an early election.

This is possible under the FTPA if a simple majority of MPs vote no confidence in their own government and an alternative government cannot be formed within 14 days. Alternatively, a two-thirds majority of MPs can call an election with a vote.

6 ways Britain leaving the EU will affect you

“For many millions of people, this was not just a vote about Europe. It was a howl of anger at politicians and institutions who they felt they were out of touch and had let them down,” Mr Farron said.

“The British people deserve the chance not to be stuck with the appalling consequences of a Leave campaign that stoked that anger with the lies of Farage, Johnson and Gove.

“The Liberal Democrats will fight the next election on a clear and unequivocal promise to restore British prosperity and role in the world, with the United Kingdom in the European Union, not out. If you agree with us, join us to make this happen.”

A spokesperson for the Liberal Democrats said people would feel “betrayed” with the outcome of Brexit and suggested the result had been won on a false prospectus.

6 ways Britain leaving the EU will affect you Show all 6 1 /6 6 ways Britain leaving the EU will affect you 6 ways Britain leaving the EU will affect you More expensive foreign holidays The first practical effect of a vote to Leave is that the pound will be worth less abroad, meaning foreign holidays will cost us more nito100 6 ways Britain leaving the EU will affect you No immediate change in immigration status The Prime Minister will have to address other immediate concerns. He is likely to reassure nationals of other EU countries living in the UK that their status is unchanged. That is what the Leave campaign has said, so, even after the Brexit negotiations are complete, those who are already in the UK would be allowed to stay Getty 6 ways Britain leaving the EU will affect you Higher inflation A lower pound means that imports would become more expensive. This is likely to mean the return of inflation – a phenomenon with which many of us are unfamiliar because prices have been stable for so long, rising at no more than about 2 per cent a year. The effect may probably not be particularly noticeable in the first few months. At first price rises would be confined to imported goods – food and clothes being the most obvious – but inflation has a tendency to spread and to gain its own momentum AFP/Getty Images 6 ways Britain leaving the EU will affect you Interest rates might rise The trouble with inflation is that the Bank of England has a legal obligation to keep it as close to 2 per cent a year as possible. If a fall in the pound threatens to push prices up faster than this, the Bank will raise interest rates. This acts against inflation in three ways. First, it makes the pound more attractive, because deposits in pounds will earn higher interest. Second, it reduces demand by putting up the cost of borrowing, and especially by taking larger mortgage payments out of the economy. Third, it makes it more expensive for businesses to borrow to expand output Getty 6 ways Britain leaving the EU will affect you Did somebody say recession? Mr Carney, the Treasury and a range of international economists have warned about this. Many Leave voters appear not to have believed them, or to think that they are exaggerating small, long-term effects. But there is no doubt that the Leave vote is a negative shock to the economy. This is because it changes expectations about the economy’s future performance. Even though Britain is not actually be leaving the EU for at least two years, companies and investors will start to move money out of Britain, or to scale back plans for expansion, because they are less confident about what would happen after 2018 AFP/Getty Images 6 ways Britain leaving the EU will affect you And we wouldn’t even get our money back All this will be happening while the Prime Minister, whoever he or she is, is negotiating the terms of our future access to the EU single market. In the meantime, our trade with the EU would be unaffected, except that companies elsewhere in the EU may be less interested in buying from us or selling to us, expecting tariff barriers to go up in two years’ time. Whoever the Chancellor is, he or she may feel the need to bring in a new Budget Getty Images

“In twenty four hours the cheap bus slogans of Farage, Johnson and Gove are unraveling,” he said.

“On £350 million for the NHS, on immigration, it is clear that they will fail to deliver what people thought they had voted for. Once again people will feel betrayed by out of touch politicians.

“The Liberal Democrats are the only party united behind a future for Britain inside the European Union.”

The striking policy to discount the referendum result is a gamble for the party, which hit a historic low of 7.8 per cent at the 2015 general election after a disastrous flirtation with the Conservatives in coalition.

That five-year period in government saw the party lose almost all of its seats painstakingly won by activists over decades, with just eight now remaining.

With the EU sure to be a key battleground in any early election, the policy may appeal to the nearly half of the voting population who voted to Remain. Over a million people have already signed an official petition to re-run the referendum, and scattered anecdotal reports on social media have shown some Leave voters already regretting their decisions.

Mr Farron, an MP from the centre-left of the party was elected to replace Nick Clegg as party chief in 2015, has previously suggested he would shy away from another formal coalition deal and lean towards confidence and supply arrangements with another party if confronted with a hung parliament.

Labour leader Jeremy Corbyn has said he will respect the result of the referendum, though his position has come under threat in recent weeks after hostile Labour MPs moved a no confidence motion against him.

Some voices inside that party have urged a rejection of the referendum, which is not legally binding. Tottenham MP David Lammy on Saturday called for Parliament to vote on whether Brexit should take place.