To get around the deadline, the women started actions for damages in the High Court, which has a six-year deadline for launching claims.

The city council attempted to have those claims struck out, arguing that under equal pay legislation such claims could only be entertained by an employment tribunal.

Law firm Leigh Day & Co described the ruling as “historic''.

In a statement it said the judgment “effectively extends the time limit for equal pay claims from six months to six years, the biggest change to Equal Pay legislation since it was introduced in 1970, with huge implications for thousands of workers”.

It said it is bringing claims against Birmingham City Council on behalf of 174 claimants, with another 1,000 claims pending in Birmingham alone.

The firm said that “there are also thousands more claims in other areas around the UK being handled by Leigh Day & Co awaiting this decision”.

Chris Benson, partner in the employment team at Leigh Day & Co, said: “This is a great day for equality and for all those women massively underpaid over many years within public and private organisations.

“Birmingham Council should now do the decent thing and settle the claims.

“They saved money by underpaying ex-workers for so many years, and so should now stop wasting taxpayers’ money fighting court cases they cannot win.”