Membership of Reform UK has surpassed that of the Conservatives as Nigel Farage declared the party is now the 'real opposition'.
A digital counter on the Reform website showed its membership tally before lunchtime on Boxing Day ticking past the 131,680 figure declared by the Tories during their leadership election earlier this year.
Mr Farage said it was a 'historic moment' as he posted on X: 'The youngest political party in British politics has just overtaken the oldest political party in the world.
'Reform UK are now the real opposition.'
He also shared a video of him celebrating the news at a Boxing Day hunt this morning.
Mr Farage said as he lifted his phone in the air: 'We've done it. We are through. How about that- the official oppositon.'
The result comes off the back of a successful year for Reform with the party claiming five seats in the general election in July, including Mr Farage taking Clacton.
The party also finished in second place in a whopping 98 seats and played a key role in splitting the Conservative vote.
Leader of the Reform Party Nigel Farage attends Boxing Day Hunt today
Responding to the surge in membership numbers, Party chairman Zia Yusuf : 'History has been made today, as the centuries-long stranglehold on the centre-right of British politics by the Tories has finally been broken.
'Nigel Farage will be the next prime minister, and will return Britain to greatness.'
There were 131,680 Conservative members eligible to vote during the party's leadership election to replace Rishi Sunak in autumn.
The figure, revealed as Kemi Badenoch was announced leader on November 2, was the lowest Tory level on record and a drop from the 2022 leadership contest when there were around 172,000 members.
However, Labour remains the party with the largest membership in the UK. It had 366,604 members as of March this year.
The Liberal Democrats, on the other hand, have around 90,000 members.
A Conservative Party spokesman said: 'Reform has delivered a Labour Government that has cruelly cut winter fuel winter payments for 10 million pensioners, put the future of family farming and food security at risk, and launched a devastating raid on jobs which will leave working people paying the price.
'A vote for Reform this coming May is a vote for a Labour council - only the Conservatives can stop this.'
British MP for Clacton and leader of the Reform UK party Nigel Farage attends the Old Surrey, Burstow and West Kent Hunt in Chiddingstone on Boxing Day
There were 131,680 Conservative members eligible to vote during the party's leadership election to replace Rishi Sunak in autumn. Pictured: Kemi Badenoch
Unlike other political parties, Reform was set up as a limited company, and in September Mr Farage announced that he would change the ownership structure so that it would be owned by members.
'I no longer need to control this party,' he said at the time.
In a video posted on X, he said: 'We will change the structure of the party from one limited by shares to a company limited by guarantee, and that means it's the members of Reform that will own this party.'
A research briefing published by the House of Commons Library in 2022 said comparing party membership numbers can be 'difficult', citing there not being a uniformly recognised definition of membership, or an established method to monitor it.
Luke Tryl, director of the More in Common think tank similarly told the PA news agency it is an 'opaque' process.
'Parties are notoriously opaque about this sort of thing,' he said, also raising the idea that it is unknown whether the Conservatives have added any mew members since their leadership election.
He later added: 'It's very opaque and murky as a metric anyway.'
With regard to Reform, Mr Tryl indicated that one of the challenges for the party will be whether membership converts to campaigners.
He told PA: 'There is no doubt Reform had a very good autumn. I think they capitalised off some of Labour's early mistakes but also the fact the Conservative brand is still struggling. They've clearly got momentum.'
Discussing Reform's membership, he later said: 'We know that lots of Reform's most vocal supporters are very online.
'Do those people who are very online and joined up... do they also go out and pound the streets, deliver leaflets, canvass, that sort of thing?
'That remains an open question.'
Reform UK party leader Nigel Farage speaks during Britain's Reform UK party's national conference in Birmingham
Richard Tice, pictured with Mr Farage, who overturned a 27,402 Tory majority to win Boston and Skegness making him one of a handful of Reform MPs
Reform's overtake of the Conservative Party's membership numbers comes amid claims that Elon Musk is poised to donate $100million to the party.
Mr Farage met with the world's richest man at US President-elect Donald Trump's Mar-a-Lago resort earlier this month.
The meeting fuelled rumours that Mr Musk, the Tesla boss and owner of X, is ready to plough some of his estimated $300billion fortune into the British political party.
The South African-born businessman has been a fierce critic of Prime Minister Sir Keir Starmer in recent months.
He has also taken a keen interest in the rise of Reform, having become friendly with Mr Farage through their shared links to Mr Trump.
Mr Farage revealed that 'money was discussed' in his meeting with Mr Musk, telling The Times: 'We are in negotiations about whether he can help. He is fully behind this.
'He is motivated enough by what's going on in Britain to give serious thought to giving money.'
But Mr Farage added the 'primary goal' of the meeting was to discuss Mr Musk's role in Mr Trump's successful bid to be re-elected to the White House.
'Our primary goal was to discuss what he did in the ground campaign,' the Reform leader said.
'There is no doubt his influence made a huge difference. I learnt a lot about voter registration.'
Earlier this year, Reform played a major part in splitting the right-wing vote at the general election in July with as many as two-thirds of the seats the Tories lost a direct result of this.
In more than 170 of the 251 constituencies lost by the Conservatives, the Reform vote was greater than the margin of the Tories' defeat.
This was the case in seats across the country, particularly in so-called 'Red Wall' constituencies snatched from Labour by former Tory prime minister Boris Johnson in 2019.
In one particularly stark example, Labour won Poole with 14,168 votes compared with the Tories' 14,150.
But Reform hoovered up 7,429 of Right-leaning votes to finish third. Just a fraction of these voting Conservative would have kept Labour out.
It was a similar story in South Dorset, where Labour won with 15,659 votes to the Tories' 14,611. Reform won 8,168 to finish third. Labour also won in Rother Valley with 16,023 votes, compared with 15,025 for the Tories.
