Who are the power players who could end up with a key role in any party split? Here are some of the names that are regularly brought up by Labour MPs and others.

Simon Franks

The 46-year-old serial entrepreneur made his fortune founding and selling businesses, including Redbus Film Distribution, which produced Bend It Like Beckham, Jeepers Creepers and others. The postal DVD rental service LoveFilm, his most high-profile endeavour, was sold to Amazon in 2011. Since then, he has turned to philanthropy, setting up the Franks Family Foundation and advising Cambodia on education. He is the driving force behind United for Change, a new political movement which plans to break the mould of politics – without recruiting existing MPs. However, his previous dealings with Labour, under Ed Miliband, make politicians who worked with him then reluctant to engage.

Jonathan Powell

The younger brother of Charles Powell, a civil servant who worked for Margaret Thatcher, Jonathan Powell joined the diplomatic service in 1979. In 1995, he became chief of staff to Tony Blair, then leader of the opposition. Powell remained with Blair throughout his time in Downing Street, and was his lead negotiator in Northern Ireland in the run-up to the signing of the Good Friday Agreement. Now working in conflict resolution, the 62-year-old has been a “sounding board” for Labour MPs who are demoralised by the current state of affairs in the Labour leadership. “After the Northern Ireland peace process, Jonathan has found something even he can’t crack: the divided Labour Party,” quips one Labour figure.

Richard Reed

The founder of Innocent Smoothies and a donor to the Liberal Democrats, 45-year-old Reed had an estimated net worth of £50m in 2016. He was particularly close to Nick Clegg, and was one of the small group of business leaders to endorse the Lib Dems in 2015, along with Rumi Verjee, the founder of Dominos Pizza; James Palumbo, the founder of Ministry of Sound; and Reg Clark, the chief executive of sports equipment manufacturer Rhino. Reed is now one of the supporters of United for Change and a vital conduit between that grouping and the Liberal Democrats.

Gina Miller

The 53-year-old worked in financial marketing for the best part of three decades before becoming a public figure following the court case in which she successfully sued the government to prevent Theresa May triggering Article 50 without a parliamentary vote. Following her legal battle, she set up a crowdfunding campaign to raise money for anti-Brexit candidates and in April 2017 launched Best for Britain, which campaigns to overturn the referendum result. The organisation credits its tactical voting campaign for a series of Conservative defeats in 2017, including the loss of Canterbury to Labour for the first time in the seat’s history, and defeats to the Liberal Democrats in Bath and Oxford West. Miller has been tipped as a possible future leader of the Liberal Democrats.

Chuka Umunna

Umunna was widely tipped as a contender to be Britain’s first black prime minister when he was first elected to the front bench in 2010. But Jeremy Corbyn’s triumph as Labour leader has left the 39-year-old MP for Streatham shut out of the front bench, and with his career in Labour in doubt. Umunna, who recently married and has a young child, retains a significant following among Corbynsceptics and as a result is frequently tipped to lead any breakaway. He has been outspoken on anti-Semitism within the Labour Party, and on his opposition to Brexit – but is seen as one of those for whom navigating EU withdrawal is a more immediate concern than preparing for life outside Labour.