The actress became a reluctant figurehead of the Time's Up movement and those fighting for gender equality when she spoke out about the fact she was paid much less than Smith - even though she was The Queen to his Prince Philip on the drama.
The revelation forced the show's bosses to publicly apologise to both stars for inadvertently putting them in a very awkward position.
And now Foy tells the latest issue of Porter Edit the whole drama was very upsetting and she had moments when she wished she didn't have to be the one making waves.
"I was deeply hurt by it, because I'd been working on that show for two years," she says. "I loved everybody on it. And then I realised, 'There's been a big, fat, dirty secret that nobody's ever talked about.' "
"But then there was also that thing (of being) an inadvertent spokesperson. Why did it have to be me? I could have said nothing. And I think everyone would have preferred that. But I thought, 'If I do that, I will be cheating myself and all the other women I know.' "
View this post on Instagram
ALL RISE: Wearing FW18’s stripped-back closet classics, actress #ClaireFoy talks about leaving #TheCrown behind, what Ryan Gosling was like as on-screen husband in #FirstMan, and why her new role as #LisbethSalander has made her stronger. Photography @lizcollinsphotographer Styling @hels_broadfoot
Foy recently dismissed reports suggesting she had been offered $225,000 (£171,600) in back pay to settle the gender pay gap on "The Crown".
In April, it was reported the 34 year old would receive a cheque to make up for the smaller salary after the huge outcry, but Claire insists she has not discussed the topic of back pay with producers.
"That was what was reported, that I was back-paid," she tells Al Arabiya. "I've never mentioned anything about it and neither have the producers. The fact that that is 'fact' is - not quite correct."