Women across the UK have been using social media to raise awareness of the gender pay gap for Equal Pay Day.

The day is observed each year based on the current gender pay gap, 17.9% in the UK, after which women are said to work “for free” until the end of the year.

The hashtag #EqualPayDay was trending across the country as campaigners and sympathisers voiced their concerns.

Carrie Gracie, who resigned from her role as the BBC’s China editor in 2017 in protest at how her pay compared to men in similar roles, tweeted: “How can you #getequal if you don’t know how your pay compares?”

Green MP Caroline Lucas pointed to research by gender equality charity the Fawcett Society, writing on Twitter: “Research… shows one third of workers don’t know it is illegal to pay men and women differently for equal work.”

Other campaigners encouraged women to Tweet using the hashtag #OutOfOffice, turning on their “out of office” notification while continuing to work to raise awareness of the day.

Catherine Mayer, co-founder of the Women’s Equality Party, tweeted: “I’ve switched on my out of office for the rest of 2018 and my Twitter isn’t working either… The gender pay gap means this is the last day until Jan UK women get paid to work relative to men. The gap is greater for BAME and disabled women.”

Clare Balding urged her followers to share information and support each other in working towards a fairer society.

“I know ‘living your best life’ is all the rage but what about ‘living in your best world’? If the system is wrong, help change it,” she tweeted.

The Fawcett Society’s chief executive Sam Smethers, said: “In workplaces all over the country, pay discrimination is able to thrive, and is more common than people realise because of a culture of pay secrecy which persists.”

Other social media users made jokes, with Nathalie Gordon, a creative at Uncommon Studios, tweeting: “If I had a pound for every time I was told that we have equal pay… Wait, I’d only get 82p of it.”

The day was first observed in the US by the National Committee on Pay Equity; this year’s date falls on Saturday November 10.

While the average gender pay gap in the UK is 17.9% that figure rises to 19.6% for women of Black African heritage, and 26% for women of Pakistani and Bangladeshi heritage.

“Today is the last day of 2018 in which women get paid to work compared to men. For Black, Asian and disabled women, they have already stopped being paid. It’s time to close the gap for all,” pointed out one Twitter user.

The gender pay gap is said to have a number of factors at play which are key to closing the gap, from pay secrecy, to women being in lower-paid sectors, to taking time off to raise children.