Actress Dame Emma Thompson joined the Extinction Rebellion protests in London after flying from Los Angeles.
In a video shared by the campaign group on Thursday, the Hollywood star urged viewers to “come and join” the demonstrations.
She said she was unable to be at the first day of the protest because she was “away” with her husband as she turned 60.
“I absolutely wanted to be arrested on my 60th birthday but I didn’t quite manage that,” she said.
“I’m so proud and thrilled to be part of Extinction Rebellion.”
A representative of Dame Emma said she needed to take the 5,400-mile flight home to London after working in LA.
She joined the protests on the day organisers announced plans to target Heathrow Airport at the start of the Easter bank holiday weekend.
Dame Emma said: “We will occupy until you take action because that’s the only way we are going to save our planet.
“We have to be here, we have to do this. It’s inconvenient for people sometimes but its much more inconvenient to leave a planet that’s so completely destroyed.”