A new update in the ongoing Asda equal pay battle could result in the supermarket forking out £1.2bn in payouts to 55,000 shopfloor workers involved in the case.

In an email leaked to ITV News and sent to all claimants by their legal team at Leigh Day, the message suggests an “independent expert” has compared the roles of predominantly women working on the shopfloor with a majority of men who work in distribution centres.

The expert scored the jobs across 11 factors including “knowledge and responsibility”, with the email claiming that shopfloor roles scored 453 points and distribution centre roles scored 447, despite distribution centre roles being paid between £1.50 and £3 more an hour.

Asda will have to answer if equal value is shown when the case comes to tribunal next year and could face a huge compensation bill.

The GMB union represents many of the claimants in the case and told ITV News that it “couldn’t comment on a leaked email”, but claimed Asda could be facing £1.2bn in historic payouts along with an increased pay bill of up to £400m each year.

GMB national officer Nadine Houghton said: “The entire retail sector has been built on the structural discrimination of women. Women’s labour has been significantly undervalued and it’s about time that society wakes up.” 

Asda claimed the report was part of a “complex case” and was confidential. Sources suggest that looking at scores across 11 different skills were not how the jobs would be compared.

A spokesperson said: “It is not a ruling by the Employment Tribunal and is not a decision on the question of equal value. At Asda male and female colleagues doing the same jobs in stores are paid the same and this is equally true in our distribution centres.

“We continue to defend these claims because retail and distribution are very different sectors, with their own distinct skill sets and rates of pay.”