During an average shift on the shop floor at Next, Helen Scarsbrook has to remain polite and keep smiling while she makes split-second judgments about which customers need help and which need to be tactfully discouraged from shoplifting and ushered out of the store.

She and her mostly female colleagues are on their feet for long stretches and regularly do heavy lifting as new stock arrives at the back of the shop. She is confident that her work in one of Next’s 466 UK stores is just as challenging, or more so, as the jobs performed by Next’s mostly male warehouse workers, who have always received higher rates of pay.

This week an employment tribunal judge agreed, in a landmark equal pay ruling that could have implications for similar claims being fought by female shop staff in some of Britain’s largest supermarkets.

The reasons given by Next for paying its shop workers less an hour than its warehouse workers were held by the tribunal to be unjustified sex discrimination. As a result, Scarsbrook and 3,539 other Next sales consultants who took the claim would have received more than £30m in compensation if the chain had not immediately announced that it would be appealing against the judgment.

A day after travelling to London to digest the ruling with her Leigh Day lawyers, Scarsdale is back at home in Southampton preparing to return to retail work on a pay rate that is at least 40p less an hour than colleagues in the company’s warehouse. She is triumphant and weary, exhausted by a legal battle that has already dragged on for more than six years.

“We always knew we weren’t well paid; retail work is never well paid. It has a bottom-of-the-rung reputation, which you get used to, but it made me furious when I understood that the warehouse workers were paid more,” she says. “I’m not saying that they don’t deserve the money, but the company needs to accept that we work as hard as them.”

She is convinced that the low status and pay accorded to shop workers is tied up with the fact that it is a job primarily done by women. “A difference of 40p an hour may not seem a lot, but 40p every hour, every day, for decades, it adds up. It just makes you feels so undervalued,” she says. “I want retail workers to get a bit more respect. I hope this judgment will inspire other women to come forward.”

Scarsbrook is reluctant to criticise a company that has employed her for almost 22 years, and where she plans to continue working. She enjoys her job, speaks warmly of her colleagues and arrives looking smart in a crisp, white Next linen shirt. But she believes the organisation has not acknowledged the degree to which its success has been built on the work of its mostly female shop staff, and she is disappointed to still receive a minimum wage rate despite decades of experience.

“They haven’t recognised women’s value. I do find that frustrating,” she says. “I remember Barbara Castle; I was at school when she passed the Equal Pay Act. I’m a pensioner now. It’s taken this long for things to change, and they still haven’t really changed. People tend to think that these battles have been won.”

After school, Scarsbrook, 68, trained as a paediatric nurse, but she found the hours difficult after having children. She took a part-time job at Next when her children were teenagers because she could make the hours fit alongside her responsibilities as a single parent. “Nobody really chooses to work in retail – people fall into it.”

Her phone is full of supportive messages from female colleagues (“Helen: you are blooming amazing”; “Thank you for helping to make this happen”) but she is disturbed by streams of negative comments from men online. Posting on Facebook beneath news of the judgment, one man said: “Well done. I hope you all feel the same way when you’re all homeless and bankrupt because of these ridiculous pay awards.” (Next reported £918m in annual pre-tax profits for 2023, up 5% from 2022.) Another put: “Ridiculous. Let the shop assistants carry huge boxes round then if they want equal pay.”

Scarsbrook says: “There’s always been this idea that if it’s a physical thing then it’s harder than the mental stress.”

The case has involved a sophisticated calculation of the relative skills and stresses involved with their jobs, with a detailed assessment of 11 aspects of the roles carried out by shop staff and warehouse workers, including everything from physical skills to problem-solving and decision-making. At the end of this calculation, shop staff scored as highly as or higher than warehouse workers. Part of the process has involved Scarsbrook explaining to the tribunal that female shop workers have to lift the same boxes of clothes that their colleagues in the warehouses do when they unpack them and hang them on the rail.

“On top of that you have to put on a smiling face and be pleasant every day as you wait to serve customers – some of whom might want to have a joke with you, or they might be in a bad mood, determined to have a fight, want to rob you, or just be on their mobile phones and not acknowledge that you are there. It’s exhausting.”

If she were to receive back pay, Scarsbrook estimates that it might total about £6,000. “Enough to pay off my car loan, take a nice holiday, perhaps cut my hours. It would make a real difference,” she says.

Next’s lawyers argued that market forces meant warehouse workers received higher rates but the tribunal concluded that “the business need was not sufficiently great as to overcome the discriminatory effect of lower basic pay”.

Elizabeth George, a Leigh Day partner and barrister representing the successful claimants, said the result was a boost for the 112,000 store staff bringing similar equal pay claims against Asda, Tesco, Morrisons, Co-op and Sainsbury’s through Leigh Day. “When you have female-dominated jobs being paid less than male-dominated jobs and the work is equal, employers cannot pay women less simply by pointing to the market and saying it is the going rate for the jobs,” she said.

In a statement, Next said the tribunal had rejected claims of direct discrimination by the company and had not accepted all claims of indirect discrimination, highlighting that the tribunal found “there was no conscious or sub-conscious gender influence in the way Next set pay rates”.

The company said: “It is our intention to appeal. This is the first equal pay group action in the private sector to reach a decision at tribunal level and raises a number of important points of legal principle.”