As poster girls go, Daisy Bata, Lucy Masoud and Natalie Linder certainly fit the bill.A cinema worker, a firefighter and a midwife, what they have in common is a fierce dedication to their jobs: they have all recently been involved in strike action to defend the services they represent. They are also part of a new majority in today’s trade unions: 55% of British union members are now women.

In a week that could help define industrial relations in this country for the next generation, the three women have volunteered to appear on billboards that will be going up around the UK to draw attention to what campaigners claim is an attempt to usher in some of the most draconian legal measures against trade unions to be taken since before the miners’ strikes of the 1980s. A mass protest rally will also take place on Monday in Westminster.

On Tuesday, the new trade union bill will come for the third time in front of the House of Commons. Those who oppose it claim it heralds a new era of poisonous relationships between employers and employees. The bill has been called “ideological and provocative” by the Lib Dem former business secretary Vince Cable, “vindictive” by Green MP Caroline Lucas, and has been compared to something from Franco’s Spain by Conservative MP David Davis. Business associations have also expressed their unease.

According to Frances O’Grady, general secretary of the TUC, No 10 is fighting old battles. “The government is stuck in some Thatcherite perception of the trade union movement: stuck in the 1980s. The world has changed; certainly the trade union movement has changed. It’s midwives, not miners, and they’re fighting for their services, the people they serve, as much as pay.

“The three women who are taking part in this campaign are astonishing examples of the kinds of dedicated people that will be worst hit in their inability to fight for their services and the people they serve.”

Business secretary Sajid Javid has said the bill is “not a declaration of war” on unions, but a necessary step to stop repeated threats of industrial action. It will lift the ban on agency workers replacing permanent workers during strikes, which has been outlawed since 1973; extend the notice that unions have to give of strike action from seven days to 14; impose a 50% turnout threshold for all strike ballots; and requires 40% of those eligible to vote in public services such as education, fire and transport to back industrial action.

Under current law, ballots follow usual parliamentary voting rules, meaning strikes can be called on a simple majority vote.

The bill would also limit the amount of time a union representative can spend representing their members. It would become compulsory for picket-line supervisors to carry letters of authorisation and wear special armbands, under threat of a £20,000 fine. Unions could also be required to give police and employers two weeks’ notice of any social media messages they will be posting – also under threat of court-imposed penalties for failing to comply.

MPs backed the bill at its second reading in September by 33 votes.

Human rights groups call it “a major attack on civil liberties”. And Bata, 23, who worked at the Ritzy cinema in Brixton and took strike action to get the living wage, calls it “depressing”.

“I think for younger people in particular, the social media aspect seems just ridiculous, unpoliceable, and shows how scared of social media people in power are. And they wonder why young people are disenfranchised from politics.

“The face of unions and grassroots opposition is changing: there’s a lot of young women now and it’s not tub-thumping any more – we want to have intelligent conversations. For me, it was so scary to take on a big company to fight for a living wage, and without the union being there to reassure us that we did have rights as workers then I’m not sure things would have changed.”

Daisy Bata in one of the TUC’s posters

Linder, 29, a midwife from Liverpool who now works in Worthing in Sussex, took strike action last year to secure a 1% pay rise. “It was never about the money. Which is why the right to strike is so important to me: midwives had never taken industrial action before – we didn’t even know we were allowed to – and it was with a heavy heart that we did. But we were being treated very badly and we weren’t being valued; it’s hard to keep up a brave face when you are so demoralised. At some point you have to stand up for yourself.

“Actually we had very respectful conversations with our managers and it enhanced, not damaged, our relationships.”

She is particularly worried about the prospect of agency workers being brought into a maternity unit. “I can imagine just the threat of that would stop midwives striking because at the end of the day our women are the most important people to us and we’d be very nervous about that prospect. It wouldn’t be safe. So that would certainly take away our right to strike.”

Safety is key too in the mind of London firefighter Masoud, 37; that is why she took strike action over retirement age and pensions. “Having a union in the fire service is absolutely essential. Firefighters have something that most politicians would die for – the respect of the public – and we are proud of that. I didn’t join the service to go on strike but when I signed up it was until I was 55. Now the government has decided I am to be running into a burning building at the age of 67 and if my fitness isn’t what it was when I was 21, then I can be sacked.

“I think that changes the picture as far as risk and public safety is concerned. We put our lives on the line every day and that’s fine: that’s what we signed up for. But if the risk is needlessly going to be increased, then it’s wrong and unreasonable.”

Masoud has seen major cuts to fire and ambulance services in London and says there is no doubt that public safety is being compromised.

“We’ll be at a road accident and have no idea if the ambulance is going to turn up,” she says. “Lives are at risk. People need to be able to say when something is not right and these draconian measures against unions are not right.”

O’Grady agrees: “The government simply wants to hobble any opposition to the very extreme second round of cuts that haven’t hit yet. And it’s throwing red meat to the Conservative back benches.” She compared the bill to “schoolboys playing at industrial relations”.

Like other campaigners, she believes women will be disproportionately affected by the bill, with nearly three-quarters of the workers in the named “important public services” – those with the highest strike-ballot thresholds – being female.

“The threat to the right to strike in all ways is an insult to the integrity of people who are putting their all into their professions and find themselves being treated like dirt,” she says. “Midwives, for example, were striking as much for respect as for the measly 1%. Unions are democratic organisations – we do have the right to exist.”

WHAT’S IN THE BILL

■ Will permit employers to substitute agency workers for strikers during industrial action

■ Will double the period of notice required for striking workers to give employers from seven days to 14

■ Will compel unions to publish a written plan of any protest, including specific social media use, 14 days in advance

■ Will require a minimum 50% turnout in all strike ballots, with public sector strikes needing the support of 40% of those eligible to vote to go ahead

■ Will impose fines on unions of up to £20,000 if their picket supervisors repeatedly fail to wear an official armband