Andrea Egan is about to attend her first conference of the country's biggest union, Unison, as its leader.

A grassroots campaigner for more than 30 years, she upset expectations when she defeated the incumbent general secretary, Christina McAnea, in December last year.

She has suggested that the union had previously been "a sleeping giant" which was too "subservient" to the Labour leadership.

But in her first interview with a national broadcaster, Egan told me her membership had a clear message for ministers: "I have been very frank with the government. When Labour came into power there was a sense of relief. But sadly we've been left wanting."

She added: "Communities are really struggling. They [Labour] haven't delivered and my election demonstrated that members were desperate to have their voices heard."

She argued that if the government didn't pay more attention to her members' concerns, Labour would pay a political price.

"I have spoken out clearly about the threat Reform brings," she said.

"It isn't us that will hand the keys to No10 to Reform - it's them, unless they change course. And drastically."

So what should the government do differently?

"They've got to start introducing progressive policies. Investment in infrastructure, pay restoration, better services, insourcing. They need to ensure that they deliver on promises they made when they came into government."

Campaigning for the union's top job, Egan described Unison's relationship with Labour as "dysfunctional".

Warming to her theme, she said her members had been "handing money over to the Labour Party and getting absolutely nothing in return".

In 2022, the country's second biggest union, Unite, elected a high-profile left-wing woman, Sharon Graham, as its leader. She emphasised her priority was her members, not political manoeuvring.

Her union still pays a high annual membership - or affiliation fee - to Labour of more than £1m a year, but at a conference next year, members will vote on whether to cut their ties with the party.

So would Egan, who was expelled from Labour for reposting messages from Socialist Appeal, a Marxist group now proscribed by the party, take a similar tack?

Egan insists that she has only ever been a Labour member - and it wasn't her choice to leave.

She tells me the 1,300 delegates at the conference in Brighton this week will discuss the relationship with the party, but won't debate "disaffiliation" – in other words severing formal and financial ties to Labour.

She said the union was "affiliated to Labour at the moment" and it would be up to members in each region of the union to decide if that was to change.

And she rejected Nigel Farage's offer to unions to affiliate to Reform UK instead.

"It's an interesting tactical move on behalf of Farage," she said.

"But look at Reform's actions in last 12 months, these demonstrate they are not on side of workers.

"If they got into government they'd attack pensions and protections in the workplace."

She said she welcomed the setting up of Your Party last year by Jeremy Corbyn and Zarah Sultana to offer an alternative to Labour on the left, but the party didn't make a huge impression at May's local elections in England.

Egan's assessment is that the disillusionment with Labour is now being expressed in a different way.

"Your Party offered people an opportunity to give Labour a warning that it needed to change. And I feel really sad that that warning is being delivered now by Reform."

She said Labour had made mistakes which alienated it from some of her members who had been looking forward to a new government two years ago: "It's not just about Labour not delivering, they were attacking our movement and our membership."

She had in mind the initial winter fuel cuts, and the delay in lifting the two child benefit cap.

More campaigning

With a Labour leadership contest likely if Andy Burnham wins the Makerfield by-election this week, would the relationship with Labour would improve with a change at the top?

She praised Burnham for his work on the rights of migrant workers – a cause close to her heart.

She, like Angela Rayner, is exercised by the government's intention to make migrant care workers already in the UK wait up to 15 years to gain permanent settlement.

She has written to the prime minister, lobbied parliament and held rallies to try to force change.

But Burnham has now said he welcomes the "broad thrust" of the home secretary's immigration changes.

I asked if that concerned her but she said her message would be the same no matter who led Labour.

"I want this scrapped now," she said.

Under her leadership, she wants her union to engage in more campaigning activity.

When it comes to industrial relations, Egan said she felt her union had previously been "a bit risk averse to taking action".

She won't be so cautious.

While she stressed that strikes must still be a last resort, at the weekend she told local government workers to prepare for ballots if a 3.3% pay increase isn't improved.

She said: "Strike action is our way of saying to employers we won't just accept crumbs from the table.

"We won't accept lower wages, and we won't accept real-terms pay cuts."

She started working in residential care for the elderly and then for children in Bolton, where she grew up and still lives.

She went on to become a qualified social worker, and in 2022 became her union's president – a one-year post open to lay members.

When campaigning for the union's top job she said she would take a social workers' salary rather than the general secretary's package, worth around £180,000.

So I asked her – a few times - how much salary she was now drawing.

She wouldn't give me a figure but she did say it was "considerably less" than the rate for the job, and she was donating the surplus to the union's industrial fund (covering strike action) and a charity, adding that her message to members was "when your pay rises, so will mine."

A full list of all the candidates standing in the Makerfield by-election can be found here.