Here's an interesting article from The Guardian's Employment Law website, listing 10 rather alarming facts about the gender pay gap in Britain.

If an employee suspects that they are receiving less pay than a comparable employee of the opposite sex, they are able to write to their employer requesting information to determine whether their suspicions are confirmed. If it becomes apparent that they are receiving less pay, and for no good reason, they can bring a claim in the Employment Tribunal under the Equality Act 2010. However, despite the ability to bring such a claim, the reality is that numbers don't lie and the gap of 14.2% is significant.

Fact 3 in this article helpfully reminds us that the issue of equal pay is a complicated one. The law surrounding this issue is not straight-forward and so if you feel that you're not receiving the same pay or benefits for doing the same work as a colleague, and are unable to resolve this complaint directly with your employer, you might want to consider taking advice from a professional.