The latest hearing in the UK’s largest ever private sector equal pay claim is due to kick off on Wednesday, in a case that could eventually see around 15,000 predominantly female Asda workers recovering well over £100m in pay.

The two-day hearing, due to take place in Manchester, follows a judgment in October last year which found that lower paid shop workers – mostly women – can compare themselves to higher paid workers in Asda’s distribution centres, who are mostly men, because their jobs are of roughly equivalent value to the company.

Asda appealed that ruling unsuccessfully but it is now appealing again.

Lawyers acting on behalf of the 15,000 former and current employees bringing the claim said that this week’s hearing will be concerned with the process for writing and agreeing descriptions for jobs that are mostly done by women and jobs mostly done by men.

If the job descriptions are deemed by independent experts to be of similar or the same value to the company, then both should be compensated equally.

Asda initially tried to stop the claims from proceeding in the employment tribunal, arguing that they should be heard in the High Court, but the Court of Appeal ruled that the employment tribunal is the appropriate place for the claims to be heard.

Linda Wong, a lawyer in the employment team at Leigh Day, who is representing the Asda workers, told The Independent that it was hard to say how long the case would last but that it had the potential to be a game-changer for gender pay disputes.

“There is pervasive gender stereotyping across the retail sector and still a huge amount of ignorance on the matter,” she said. “However long this case goes on, one thing that it is doing is raising awareness.”

According to official statistics, the gender pay gap for full-time employees in 2016 was 9.4 per cent, largely because of a tendency for women to take on more caring responsibilities and work part-time.

The gender pay gap for both full and part-time employees fell from 19.3 per cent in 2015 to 18.1 per cent in 2016, but campaigners are saying that the pace of improvement is still much too slow.

In April, legislation was introduced giving companies that employ at least 250 staff a year to publish comparative pay rates for male and female employees.

Six months to go until that deadline, however, only 1.2 per cent of companies have divulged their figures according to the Chartered Management Institute.

Ms Wong said that she welcomed the new pay gap reporting rules but that they were unlikely to be a silver bullet to the issue.

“It’s still not clear what penalties there will be for companies who don’t report,” she said. “Really holding companies and employers to account will only be possible if there is case law precedent.”