10/03/2015 13:27 GMT | Updated 10/05/2015 06:59 BST

It's Up to All of Us to Make Sure That Pay Transparency Finally Spurs Equal Pay for Women

Today the fight for equal pay just got a little bit easier for millions of working women across the UK. I say today, in fact it will be roughly a year today, once the government has had time to consult and bring in the regulations. But the principle has been won. After many months of campaigning by the Labour Party, Grazia magazine and others, the Conservatives and Lib Dems have finally acknowledged they have been on the wrong side of history - and a vote they looked likely to lose - so will be accepting Labour's amendment to the Small Business, Enterprise and Employment Bill in the House of Lords, to introduce pay transparency for all large employers.

Pay transparency is a simple measure, but sometimes simple changes are the most powerful. Once implemented, employers of over 250 workers will have to publish details of the average pay of their male and female employees, meaning for the first time, women will be able to see if they are being paid less than their male colleagues.

Women still earn on average just 81p for every male pound and the rate at which the pay gap is closing has slowed under this government. In fact, if we'd continued to make the same progress we were under Labour women working full-time might be over £100 a year better off.

The big question is why has this taken so long? In 2010 the then Labour government included powers to bring about these rules in the Equality Act, but one of the first things the Conservatives and Lib Dems did in government was to shelve this. Transparency was a step too far they claimed. Liberal Democrat Lynne Featherstone, who was equalities minister at the time, claimed that a voluntary approach would "secure more buy-in and achieve more lasting change than the big stick of legislation" and that it "is not about forcing companies to report information they don't want to."

Well in some ways Lynne Featherstone was right, just five companies in five years decided to report information on their gender pay gap. These five companies: Genesis Housing, Friends Life, PwC, Tesco and Astra Zeneca deserve credit. It's not easy to stick your neck out and be the first in your field to acknowledge your gender pay gap. But these employers recognise that tackling the thorny issues around why women are still paid less than men, why there are fewer women at the top of the company and where subconscious bias and discrimination can still play a role, ultimately make a company more attractive to talent, and more profitable.

According to the chair of PwC, Ian Powell:

"By improving transparency and accountability, there is greater opportunity to understand whether opportunities are equal for all across a workforce and whether further action needs to be taken." When asked why they reported, insurers Friends Life responded that "it builds on the old adage, "what gets measured, gets managed" - we take a more robust view that "what gets publicly reported, gets managed better."

When the women machinists of Ford Dagenham won their battle for equal pay in 1970 with the Equal Pay Act, they believed they were changing history for their daughters, their nieces and sisters who came after them. I had the privilege of meeting four of these extraordinary women, Gwen, Eileen, Sheila and Vera, back in December when they came to Parliament with Grazia magazine to support Labour's motion on equal pay in the House of Commons. They said to me, we never thought 40 years on we'd still be fighting this battle.

It's up to all of us to make sure that pay transparency finally spurs the action necessary, to give Gwen, Eileen, Sheila, Vera and women across Britain the victory we've been waiting for.

Gloria De Piero MP is Labour's shadow minister for women and equalities