Female activists took a group of male swimmers by surprise on Friday evening when they attended a men-only swim session wearing just trunks and pink swimming caps.

Amy Desir, 30, was one of the two women to gain access to the south London pool session, as part of a protest against proposed changes to the Gender Recognition Act, which would enable men and women to choose their own gender.

Both women explained their attendance to staff at Dulwich Leisure Centre by saying they “identified as male” and subsequently had the right to be there.

Amy Desir: ‘Misogynistic and homophobic pro-self-ID policies are allowing men to appropriate women’s spaces, services and positions’ (Amy Desir)

They also used the male changing rooms before going into the session and were later asked by an elderly man if they realised it was a male-only session.

Their actions form part of a nationwide campaign formed on Mumsnet called #ManFriday which encourages women to “self-identify” as men every Friday in protest of the proposed amendments to gender laws, which would enable people to self-identify as men or women.

“The aim of the group is to raise awareness among men of the misogynistic and homophobic pro-self-ID policies that are allowing men to appropriate women’s spaces, services and positions,” Desir told The Independent.

“Most men either aren’t aware of the issue or don’t think it has anything to do with them.”

There are currently 91 women taking part in #ManFriday, revealed the mother-of-two, all of whom self-ID as men every Friday to access men-only spaces.

“We don’t change anything about our appearance, or pretend to be in the process of transitioning, just state that we are men.”

Desir and her fellow campaigners are concerned that the proposed legislation would enable predatory men to abuse women in single-sex spaces by self-identifying as female.

Mumsnet’s #ManFriday campaign currently sees 91 women in the UK self-ID as men every Friday (Amy Desir)

“We want to challenge the idea that sex and gender are interchangeable and for organisations to use the lawful exemptions in the Equality Act to protect the rights, safety, dignity and privacy of women,” Desir added.

“We also want women’s organisations to be consulted on proposed changes to the law.”