Parliament will read a Labour bill today calling for businesses to be more transparent over what they pay men and women.
The party claim the pay gap has resulted in women earning £210,000 less over a lifetime than men.
Labour MP Gloria De Piero spoke to London Live about the bill, which calls for companies with more than 250 employees to publish any pay difference between men and women doing equivalent work.
By shining a light on the situation, they hope to resolve the problem.
Former Bond girl Gemma Arterton was at the protest in solidarity with veterans from the 1968 Ford factory strikes, which saw workers strike for the Equal Pay Act.
Their story was adapted for the film, Made in Dagenham, and the subsequent musical which Ms Arterton is now starring in on the West End.