Iain Duncan Smith, Dominic Raab and Theresa Villiers are among a swathe of Conservative MPs at risk of losing their seats if the Tories face a resurgent populist party led by Nigel Farage alongside a Labour swing at the next election, experts have said. Their constituencies are among hundreds of Tory-held ones where the Brexit party did not stand in the 2019 general election, but the already slim majorities would be destroyed by the Reform UK candidates attracting even relatively small numbers of voters. They include more than 30 Tory-held seats alone – many in supposed “blue wall” areas of southern England – where the sitting MP is already defending a majority of less than 10%, according to analysis of data from the House of Commons Library. “There’s a significant slice of seats where the Conservative majority over Labour or the Lib Dems is not large, and there was no Brexit party candidate last time. If a Brexit party-type candidate stands next time then the Conservative MP is struggling even before any swing to the local opposition,” said Prof Rob Ford of the University of Manchester, the author of The British General Election of 2019 and Brexitland. A return to frontline politics by Farage – now a broadcaster with GB News but who has dropped hints he may come back – is the necessary caveat from Ford, and others such as Prof John Curtice, for a scenario in which Reform is able to capitalise on recent polling – such as a YouGov finding putting the party on 9%. “Reform UK need Farage to come back, and if he did – given that there is an immigration issue for him to leverage – then the Tories would have good reason to be concerned,” said Curtice, a professor of politics at the University of Strathclyde, who added that Reform UK was the means by which Brexit-supporting voters could register their displeasure at Conservative economic mismanagement while remaining true to their leave credentials. Farage is listed on Companies House as a “person of significant control” of Reform UK, which is registered as a limited company and has been led by the businessman Richard Tice since March 2021. However, the fall of Boris Johnson and scepticism about the Brexiter credentials Jeremy Hunt, who backed remain, and Rishi Sunak, who voted to leave, have fuelled speculation of a Farage return at the same time as a small but steady stream of disillusioned Tory voters and former members have been joining Reform UK. While the party claims thousands of Conservatives have been joining, a weekly trickle appears to be at least evident on Facebook pages where Tory defectors are announced and congratulated. Sources close to Farage say he is weighing up whether to return imminently or wait until a Labour government moves to introduce proportional representation, which would pave the way for MPs from a new radical right party, such as Reform UK or a renamed version. Tice did not rule out a return by Farage when the Guardian floated to him the scenario of the latter becoming “chief executive” with Tice as “chairman”. The former Ukip leader was “a busy guy with GB News”, Tice said, adding: “No one’s more furious about the state of the country than someone like Nigel who spent 25 years of his life trying to get to Brexit to present their platform of opportunity and then seeing that others have wasted it.” However, he was unambiguous in stating that Reform UK was “absolutely committed” to standing everywhere, apart from in Northern Ireland. “The best thing for the country would be if we get rid of the Conservatives and I hope that we are seeing the dying days of the last ever majority-Conservative government in my lifetime,” said Tice, who anticipated the “key thing” would be the introduction of proportional representation in three or four years. Reform UK has preplanned the rollout of a range of policies over the coming weeks in an attempt to capitalise on polling momentum, despite a disappointing showing in the recent Chester byelection in which the party secured just 2.74% of the vote. • This article was amended on 26 December 2022 to clarify that Rishi Sunak voted to leave the EU.