Defying all expectations, the Left has a new rockstar: Mick Lynch, general secretary of the National Union of Rail, Maritime and Transport Workers (RMT). After being catapulted into the media spotlight by the biggest wave of strike action on Britain’s railways since the 1980s, Lynch immediately proved himself more than a match for the corporate journalists and anti-worker politicians against whom he was pitched. In part thanks to his level-headed delivery and dry humour, opinion polls suggest that public support for the strikers is both surprisingly high and increasing after no resolution to the first three walk-out dates last month.

Lynch may be an effective figurehead, but the real dynamism lies with the highly active workforce which makes up the RMT’s membership base. Conservatives and free-marketeers often complain that the railways are stuck in the past, characterised by labour costs which have been unfairly and inefficiently shielded from the liberalisation wave in other sectors. For progressives, this should be a source of pride. Through a combination of structural advantage and industrial militancy, railway workers have retained living standards much more in line with price inflation than the Wild West labour conditions in hospitality, social care, cleaning, and other occupations. The RMT is a proof of concept for why trade unions work, and why they are needed in all areas of the British economy.

This makes the response of the present Labour leadership all the more craven. With unions unusually topping the news agenda, Keir Starmer and his team had the opportunity to express their support for the strikers and the wider role of unions in distributing wealth more equitably across society. Instead, the leader’s office imposed a red line on shadow ministers appearing at picket lines and showing solidarity with RMT workers. This diktat provoked considerable backlash from Labour MPs and grassroots members alike, including those not generally opposed to Starmer’s leadership.

Granted, this is nothing new. The RMT formally disaffiliated from Labour during the Blair years due to the party’s Rightward drift, which somewhat simplified matters. RMT leaders can criticise the party from the Left when it fails to stand up for workers’ interests, and Labour politicians like Sadiq Khan can safely play to anti-strike sentiment when industrial relations on the London Underground periodically break down.

Things are much more awkward when it comes to the unions still affiliated with Labour, who also contribute a hefty component of party funding. Unite’s new general secretary, Sharon Graham, has made it clear that there are no blank cheques available for Labour; union money won’t be spent in politics unless it directly benefits workers, both existing Unite members and those the union seeks to organise. It would be very bold for Starmer to take a similarly hard line against industrial action coordinated by party-affiliated unions. Condemning the RMT is cowardly but, potentially, tactically wise. That fudge won’t be available as more and more workers begin demanding pay rises to keep up with spiralling inflation.

Beyond the financials and short-term positioning, there is a deeper philosophical question. The Labour Party was founded by unions and socialist groups at the turn of the 20th Century precisely because there was no effective voice for working people in Parliament. Unions had tried for decades to make the Liberal Party live up to its claim to represent everyone, including the working class, but the weight of successive betrayals became too great to bear. A similar contradiction afflicted party-union relations during the New Labour years, and is at risk of re-emerging now as Starmer aims to emulate 1990s electoral strategy. Labour’s last stint in office did virtually nothing to help workers organise into unions and advance their own interests via workplace democracy. Under such circumstances, it becomes very hard to differentiate a Labour government from centrist-liberal administrations like Emmanuel Macron’s in France, who hold in general contempt grassroots opposition to corporate interests.

Of course, that may be precisely where the party leadership and a critical mass of members want Labour to go. There is, however, scant evidence that this is what the majority of the country needs or wants from its next government. Lynch, unlike Starmer, has captured the public mood of outrage at an economic system which bears no relation to how most of us like to think society works. Before gearing up to oppose a summer of strikes, the Labour leadership should take a moment to consider whose side they are on - and how this will look come the next general election.

James Bartholomeusz is a Young Fabian and works in campaigns and policy at a global union federation. He writes here in a personal capacity.