On Tuesday afternoon, six women, all Polish, sit around a table in a small cafe near Waterloo Station in London. They are at the end of their shifts as room attendants – chambermaids in a previous era – at the four-star Park Plaza Hotel County Hall, a five-minute walk from Westminster. They look exhausted.

Cleaning at their hotel, like many services, is outsourced. Four months ago, as employees of Hotelcare, “where first-class service comes as standard”, they were paid £6.50 an hour to clean 13 rooms in eight hours, every day, five days a week– a long way short of the London living wage of £9.15 an hour. Then the contract was taken over by another cleaning services company, WGC, “servicing over 10 million hotel rooms a year”, including Claridges and the Hilton. The women say they were assured there would be no change. Now, they clean 15 to 17 bedrooms in seven and a half hours a day; more work, less pay.

This meeting is to decide whether to strike. If the strike goes ahead, it will be the first by room attendants in London for 15 years. The company’s reasoning for the change is: “It’s a hard economy.”

One woman in her 40s, who has worked at the hotel for several years and understands the financial calamity industrial action might involve, says: “It is not if we strike. It is when.” The women decide they have had enough.

About 100,000 people work in the London hotel sector, which includes small boutique hotels but also large global chains such as Hilton, InterContinental Hotel Group (IHG) and Meliá. The sector is often referred to as the Bermuda triangle of union organising. No collective agreement has been signed since the 1980s. Any attempt to unionise can lead to wholesale outsourcing of a department, job cuts and repercussions.

“I asked for a paid break,” says Carol, studying part-time and working on zero hours at a different hotel, “and the next day I was sent home and told there was no work. You soon learn.”

The room attendants from the Park Plaza Hotel range in age from 20 to 59; a number have left children in Poland or have long commutes, so leave home before the family is awake. Each has her own collection of stories about how the work has built up since WGC took over the contract. One, last week, found a number of her rooms still occupied by guests – known as DNDs, short for Do Not Disturb – so she could only clean four rooms by noon. The supervisor, “yelled and screamed but she knows how it works”.

Another says she had seven sofas (in family rooms) to turn down and asked for extra time. “Ten minutes, the supervisor gives. Not for one sofa, for seven.”

A third tells how if you say you are sick, “they say go home, no pay”. The gap between official policy and the petty harassment and bullying that actually occurs is wide. Supervisors and trainers have the power.

“Saturdays are the busiest days,” says another woman. “I have to clean a bathroom, kitchen, bedroom for four people; sometimes, what we have to clean up is horrible. Change sheets, clean the microwave and all the time the supervisor is there with a time sheet saying faster, faster.” The time taken to clean a room is between 24 and 28 minutes, depending on the hotel.

“I waited an hour and a half for my allocation of rooms,” says one woman. “We want to work well but if you are watched, timed, shouted at,” she shrugs. “We can do 13 rooms. More? No.”

London has more than 136,000 hotel rooms and, according to accountant PwC, they have an occupancy rate of 84% and a mean cost of £145 (£5 higher than last year). This means a potential yield of £122 per room per night. Yet room attendants are paid between £2.30 and £3.75 per room.

One woman tells how she worked for a cheaper chain and, illegally, was paid a piece rate – £2.17 a room, 25 rooms a day. Another says that if her allocated rooms are not completed in time because guests are late departing, she has to work the extra time, unpaid.

Ewa Jasiewicz outside the Grosvenor House hotel on Park Lane, London. Photograph: Richard Saker for the Observer

Ewa Jasiewicz, 36, is one of two part-time organisers who, supported by Unite, have since January been working to unionise hotel workers, using a system developed in New York that has proved highly successful, and has forged links with other unions as well as faith and community organisations.

Many London staff will not picket a hotel for fear of CCTV surveillance. They know that some hotel chains police social media for “contract infringements” (by which they mean criticism of management). The chains deter union activity. Jasiewicz was headhunted to set up Hotel Employees Action Teams (Heat) and organise weekly “actions”. She looks out for employees potentially sympathetic to the union and these workers, in turn, are trained and attempt to recruit five more members. It is undercover work. Membership of the hotel workers’ branch, begun eight years ago, has now reached 1,000.

Jasiewicz, dynamic and indefatigable, has a background that includes working as an organiser in the UK aviation and food industries, in the oil industry in Iraq, and as a peace activist in Palestine and Afghanistan. “We need a new social movement to change toxic economic relationships,” she says. “Hotel workers are the most marginalised and the most isolated. People come here from other parts of the world for work. They think they will stay for a short time. Then they make ties. They work so hard, they commute long distances, they have no time or energy to improve their language, to develop their skills, and so they become trapped. The work of a room attendant, for instance, looks simple, but it is lonely, repetitive and there is constant pressure to perform quicker.” A recent survey found that eight out of 10 room attendants had musculoskeletal problems. “The Polish prefer painkillers from home,” says Jasiewicz, from a Polish family but born and raised in England. “They say they are stronger.”

Every Monday at Unite in central London, three men, all retired, all lifelong union members, work as volunteers, holding an advice centre for London hotel workers and representing them, if necessary, in disputes. They favour grassroots “bottom-up” organisation to traditional top-down union direction. Kevin B Curran, 60, a tree surgeon, is chair of the branch. He was once a welder and was briefly general secretary of the GMB. “What we need,” he says, “is a coalition of the disadvantaged.”

He works alongside Hugh “Hughie” O’Shea, 67, a former butler and, since retiring, branch secretary. He has been negotiating with WGC on behalf of the Plaza room attendants. “The sector is addicted to low pay,” he says. “Like with all addictions, until it’s recognised as a problem there is no solution. But, for the people on the lowest rungs, that’s a social disaster.”

The third member of the trio is John Byrne, 71, once a musician in an Irish showband, then a porter, and finally a building supervisor before retirement. A grandfather to 28, he is the branch’s health and safety officer. He talks of a recent case in which a woman who had worked full-time as a housekeeper for nine years had unwittingly signed a new contract. Too late, she realised that her five-day week had been reduced to two. “If you don’t know your rights, you don’t know what you are entitled to fight for,” he says. “If we don’t do this, who will?”

Unite union members John Burn, Kevin Curran and Hugh O’Shea. Photograph: Richard Saker for the Observer

While there are excellent employers in the hospitality industry, and some employees are nothing but trouble, the weekly clinic reveals just what happens when unions are weak, levels of immigrant labour are high, and the appetite for profits appears insatiable. A luggage porter in a five-star hotel has a recording of his manager, on several occasions, talking to him in a threatening and insulting manner: “He wants me out.” The porter has complained but so far there has been no action. His son, aged four, sits opposite him as he talks. “The stress makes me feel like crying,” he says. “But I won’t in front of my boy.”

A housekeeper from Ivory Coast who has worked without complaint for nine years was told her performance is unsatisfactory a short time after telling her line manager that she was pregnant. “I am a five-star employee working in a three-star hotel,” she says.

A Spanish night receptionist, a geologist by trade, earning £17,000 a year, says over six years, staff have been cut and the workload increased while his pay has risen by pennies. He is now a member of Heat.

A few days before Tuesday’s strike meeting, a group of around 20 people gathered outside the Grosvenor House Hotel in Park Lane. They were there to commemorate a milestone on the road to poor conditions. Thirty years ago, members of its banqueting staff were dismissed for attempting to join a union. At the core of employment law is “mutuality of obligation”. The employer is obliged to offer hours; the employee is obliged to work those hours. However, Derry Irvine QC, later Labour lord chancellor, successfully argued that the banqueting staff had been employed as casuals, and therefore the mutuality of obligation did not exist. This decision opened the door to zero-hours contracts.

Inside the Grosvenor House, the Ivor Novello awards were being celebrated, with Ed Sheeran and Clean Bandit among the award winners. Outside, observed by hotel security men, Jasiewicz leads the chants. “Five stars for guests. Zero stars for ethics! No union. No peace.” Only two guests, smoking outside, ask about the demonstration.

Alongside Jasiewicz, Curran, Byrne and O’Shea was Dave Turnbull, 56. He was a chef before becoming a full-time union official. He is now London and Eastern Area regional organiser (hospitality sector) for Unite. He charts a number of small successes: The InterContinental Hotel Group, for instance, promised to introduce the living wage over a five-year period to 2018.

In the main, he said, conditions of employment have seen a marked deterioration. “The decline in manufacturing has taken with it an understanding of industrial relations on the part of employers. Now, hotels and restaurants are property-based franchises belonging to hedge funds and private equity firms: they own the brand and the building but have little concern for employees; the shareholder comes first.” He added: “We believe the living wage would have a positive impact on the problems of high staff turnover and skill shortages that have plagued the sector for decades. It is also the right thing to do.”

Hospitality is Britain’s fourth-largest industry, worth more than £60bn a year. “The best way to protect the future is to shape it,” writes Ufi Ibrahim, chief executive of the British Hospitality Association in its annual report. But on its website, under “Responsible Hospitality”, there is no mention of work and conditions for employees.

“The debate on the living wage is out of step with the reality of our industry, which is heavily dominated by small to medium enterprises,” Ibrahim says in response to the Observer. “These make up 80% of our industry … The overall impact would be a staggering £33bn … resulting in more losers than winners.”

It may seem like a compelling economic argument, but a start could be made among the 20% that is made up of global hotel chains. It has worked in New York. Jim Donovan became a waiter at the Carlyle Hotel, close to Central Park, in 1980 and a full-time official of the New York Hotel and Motel Trades Council in 1985. The union for hotel workers is part of Unite Here, which, in central New York, is divided into eight locals. Donovan is president of Local 6, which has 23,000 members, speaking 67 languages.

The union is about to ratify an extraordinary agreement between its members and the major hotel chains (around 71% of the city’s hotel rooms). The deal runs to 2026 and represents room attendants, housekeepers, cooks, dishwashers and others. A non-unionised housekeeper can earn just over £7 an hour. In Local 6, the rate is £16 an hour and higher, with health cover, holidays, controlled hours and access to training and education.

Unionised room attendants also see their quota of rooms drop from over 30 to 12 a day, and that reduces turnover, training and recruitment costs, stress and days lost to ill health. “We’ve fought for the best deal in the world,” Donovan says. “Employers see it now as a middle-class profession, treated with dignity.”

Such victories are rare but they matter, and they also underline the importance of consumer clout. In New York visitors can consult a list of “Fair Hotels” – those that are unionised with decent employment standards. Hotel guests and conference organisers are reminded that their choices they make change peoples’ lives, and exhorted to “Sleep with the Right People”.

In the UK, all the hotel chains the Observer approached gave similar responses except for WGC, which declined to comment. Zero hours are a flexible “choice” for employees and low pay is only an entry point. Yet nationally, 25% of minimum-wage employees have been in that position for five years.

Hotels that outsource cleaning, for instance, deny responsibility for the working conditions of those employed under their roofs. PPHE Hotel Group, owner of the Plaza County Hall, says it is its policy “to work solely with ethical suppliers, and that the group’s priority remains the delivery of an outstanding guest experience and the wellbeing of its guests and team members”.

It’s corporate speak. Meanwhile, in Torquay, Devon, the award-winning Haytor Hotel, with 14 bedrooms and a staff of five, including owners Roger Ashman and Peter Holcroft, runs a successful business. It charges £69 to £150 a night and is the UK’s first accredited living wage hotel. “It’s important that one person’s luxurious stay isn’t funded by another working for poverty wages,” Ashman says. “What’s rewarding is that some people choose us because we pay the living wage.”

On Friday, it was unclear whether the Plaza County Hall’s “team members” include its room attendants. Numbering 42 in total – 16 Polish and the remainder mainly Romanian and Hungarian – they will now be balloted on strike action. What is clear is that the wellbeing of the six who came to the Observer to be photographed, in case of management reprisals, was far from evident.

“We want what is fair,” one woman, who has worked at the hotel for several years, says. “So, we have to strike.”

Unite’s hotel workers branch welcomes recruits and activists: facebook.com/hotelworkersunite