People travel by tube on the London Underground to take part in the Pride in London parade, London, Saturday, July 1, 2023. (Photo by Jordan Pettitt/PA Wire via AP Photo)

London Mayor Boris Johnson takes part in a tug of war with members of the armed services to launch the London Poppy Day, outside City Hall, in London, October 27, 2015. London Poppy Day is a street collection event to raise money for serving and retired members of the armed services and their families. (Photo by Stefan Wermuth/Reuters)

British model Jourdan Dunn and London-based hair stylist Issac Poleon attend an event to celebrate the Maximilian Autumn/Winter 2022 collection in The Green Room at The Londoner Hotel on February 20, 2022 in London, England. (Photo by David M. Benett/Dave Benett/Getty Images for The Londoner Hotel)

The photo project was done for the organization Fishlove and included some other U.K.-based celebrities posing in the buff with critters ranging from bass fish to sharks. Its goal is to raise awareness of how overfishing is destroying the oceans. The release of Gillian's nearly nude pic, which was snapped by French portrait photographer Denis Rouvre, is timed with a European Parliament vote on banning destructive forms of deep-sea fishing in the Northeast Atlantic. The Fishlove organization is trying to rally voters to sign a petition ending deep-sea trawling – which, according to scientists, is negatively impacting the fish population and their habits – and Gillian solicited signatures in a Twitter post. Photo: “Fish Love” Project by Photographer Denis Rouvre. Gillian Anderson. (Photo by Denis Rouvre)

A model presents a creation at the Nasir Mazhar catwalk show at London Collections Men in London, Britain June 11, 2016. (Photo by Neil Hall/Reuters)

A keeper stands next to llamas during the Annual Stocktake at ZSL London Zoo in London, Britain February 7, 2018. (Photo by Tom Jacobs/Reuters)

Danielle Sellers attends The Beauty Awards at Tower of London on November 28, 2017 in London, England. (Photo by Lia Toby/WENN)

A model displays a creation during the Sophia Webster presentation at London Fashion Week, in London, Britain February 19, 2018. (Photo by Paul Hackett/Reuters)