More than 3,500 current and former workers at Next have won the final stage of a six-year legal battle for equal pay.

An employment tribunal said store staff, who are predominantly women, should not have been paid at lower rates than employees in warehouses, who are typically male.

Lawyers for the shop staff described the judgement as “hugely significant” and the amount of back-pay owed could amount to more than £30m.

However, Next said it would appeal against the ruling.

Next argued that pay rates for warehouse workers were higher than for retail workers in the wider labour market, justifying the different rates at the company.

But the employment tribunal rejected that argument as a justification for the pay difference.

It means women such as Helen Scarsbrook, who has worked for Next for more than 20 years, are in line to receive thousands of pounds of compensation for the pay they missed out on.

The 68-year-old from Eastleigh, near Southampton, one of the lead claimants in the case, said she was grateful that the tribunal had found in their favour.

“Anyone who works in retail knows that it is a physically and emotionally tough job,” she said.

“We do lots of heavy lifting, the same as the men do in the warehouse. We lift the same boxes they lift.”

Add to that the unpredictability of customers who are sometimes wonderful but sometimes challenging, she said.

“It’s an enjoyable job, but it’s not easy and it’s really undervalued financially and I just thought ‘it has to stop’,” she told the BBC.

Ms Scarsbrook put in her claim in 2018 and should receive compensation for being paid less than her male counterparts in the warehouse going back six years, to 2012.

It is likely to amount to several thousand pounds, which would let her pay off her car loan, take a “very nice” holiday or perhaps retire, she told the BBC.

Elizabeth George, barrister and partner at the law firm Leigh Day representing the workers, said the ruling would come as a “huge encouragement” to workers in other sectors.

“Retail isn’t the only sector where you have jobs that are divided along clear gender lines and you see the male-dominated market is attracting a higher rate than the female-dominated roles,” she said.

Workers at five of the UK’s largest supermarkets, Asda, Tesco, Morrisons, Sainsbury’s and the Co-op, are also pursuing equal pay cases, with the firms using the same arguments as Next around market pay rates to counter them.

Ms George said she believed the judgement could prompt further cases, for example in the care sector, hospitality or construction.

There have already been cases in the public sector over lower pay for workers, including teaching assistants and dinner ladies paid less than men employed in refuse collection and similar roles.

In a statement, Next said: “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.”

The firm emphasised that no cases alleging direct discrimination against female staff were upheld and that the tribunal found “there was no conscious or sub-conscious gender influence in the way Next set pay rates”.

More than 80% of Next’s store staff are women.

Barrister Ms George said: “[The tribunal] rightly found that Next could have afforded to pay a higher rate but chose not to and that the reason for that was purely financial.”

The argument around market rates was essentially “circular” Ms George said, suggesting women should be paid less because they were already currently being paid less elsewhere.

Leigh Day said that the claimants’ contracts would now be changed to reflect fairer rates of pay.

In other areas where there was a mismatch, for example over different ways of calculating night payments, paid rest breaks for warehouse staff and Sunday pay, better terms would also be extended to shop staff.

However, it was not yet clear whether other staff, not directly involved in the case, would see their employment terms upgraded automatically, she said.

The process of calculating what claimants were owed as back-pay should begin as soon as possible, said Ms George.