Popular dating app Happn was taken over by children's charity Plan UK on 23 November in a campaign to raise awareness about child marriage. Instead of seeing profiles of other single people in the area, Happn users in London were presented with only one profile on their feed. The stunt aimed to highlight the fact that many girls around the world are not given an option about who they marry.

When London users clicked on the fake Plan UK profile, otherwise known as "32-year-old Mark", they were directed to a message that read: "When we're free to date whoever we like, it's hard to imagine only having one option. So whether you like Mark or not, he's sticking around."

Happn has more than 400,000 users in London, all of whom would have come across the child marriage awareness campaign if they attempted to find themselves a date on 23 November. Plan UK notes that child marriage affects 15 million girls around the world every year, contrasting sharply with most women and girls in the UK who are free to choose their marriage partner.

A recent study conducted by Plan UK revealed that Bangladesh, Pakistan and Indonesia are among those countries where girls are most at risk of child marriage. The report, Getting The Evidence: Asia Child Marriage Initiative, revealed one in four girls in Bangladesh are married by the age of 14.

"We're delighted to work with Happn on this innovative stunt," said Tanya Barron, CEO of Plan UK. "Our work in Bangladesh, Malawi and Guatemala has shown that the first step to successfully ending child marriage is to break the silence on these issues. Through collective action, we can bring an end to child marriage and empower girls to fulfil their own potential."

Happn users in London quickly began taking to social media to applaud the "powerful" campaign. The French dating app has been growing rapidly, adding 1.2 million users every month and expected by many to catch up with Tinder by 2017.

Marie Cosnard, head of trends for the app, said: "We're proud to offer our users choice – the choice to rediscover people they've passed in the street or in their favourite coffee shop, the choice to date if they connect with someone, or the choice to say no and meet someone else – and we believe everyone should have that right."