The group also said that although the gap is wider for women in their 50s, it is also growing among younger women from 1.1 per cent in 2011 to 5.5 per cent this year.
"That is why we have introduced a legal requirement for all large employers to publish their gender pay and bonus data by April 2018".
Sam Smethers, Chief Executive of The Fawcett Society said "The pay gap is widest for older women as it grows over our working lives but we are now seeing a widening of the pay gap for younger women too, which suggests we are going backwards and that is extremely worrying". In 2014, the pay gap was at 14.2% (the mean average for full and part time workers) and since then, for the past three years, it has been 14.1%.
The Fawcett Society, which campaigns for women's rights, issued the warning as it dubbed Friday Equal Pay Day - saying it marked the time in the calendar year when women start to work for free due to their pay lag on male earnings.
It could take over 100 years to close the gender pay gap if progress remains at current levels, a charity has warned. "During that time the gender pay gap has reduced, but it has not reduced enough".
The pay gap is a measure of the systematic disadvantaging of women caused by early gender stereotyping, occupational segregation and gender blind politics that drives a wedge between men and women. We will require all public authorities with more than 20 employees to publish their pay gap every two years and an equal pay statement every four years. But even without a thorough breakdown of evidence, young women in the United Kingdom have every reason to believe that they will receive equal pay; the gender pay gap from women aged 22-39 is negligible. Economic empowerment is the key both to closing the pay gap and ending violence against women.
"This will help to address the unequal impact of caring roles which is one of the key drivers of the gap".More news: UK's May maintains cabinet balance on Brexit
We have established a women returners scheme, to support women to regain the confidence and skills they may have lost during career breaks.
What Can Be Done?
Speaking at a discussion on equal pay on Friday, Ms Bacik underlined the urgent need to build transparency around how much organisations pay their staff in order to close salary gaps between male and female employees. "We need to teach young men that it's ok to talk to women and not ok to objectify women".
Nicky Morgan, Conservative MP said "We've seen the best employers make ground breaking strides in tackling gender inequality".
Tomorrow's Equal Pay Day is a test of whether the old political parties have been paying attention.
'We represent the women who are being paid unfairly and often not being paid at all - either for their domestic labour or care duties - or because they have been fired for getting pregnant.