Carol-Anne O’Callaghan is speaking to me from her campervan. “I call it my mobile office,” she says. “It’s great. I have wifi and a desk. I even have a loo!” It is covered in bat pictures, as a nod to her activism. The 60-year-old former teacher from Great Missenden in the Chilterns, Buckinghamshire, uses the van as a base for her campaign work, which started in February 2021. O’Callaghan was walking her dogs when she spotted yellow dots stuck on some of the 99 oak trees in a narrow country lane close to her home. The dots, she learned, indicated trees marked for destruction. O’Callaghan loved that ancient line of oaks. She gets choked up remembering the moment she realised many of them were destined to be felled. They were planted in the 19th century on Leather Lane. “My family and I would picnic under them,” she says, “climb them, have rope swings on them. The trees are amazing and beautiful and meant so much.” One of the last photos of her mother, taken shortly before she died, was of her sitting in a swing in their branches. The trees were to be cut down as part of the HS2 high-speed railway works. O’Callaghan says she called the HS2 helpline and was told there was nothing that could be done. The trees were to be felled the following month so HS2 subcontractors could build an over-road. “I said: ‘Why? Why are you taking the trees?’” O’Callaghan had spent her career as a teacher telling children that “If something is wrong, you can’t stand by and let it happen. You have to speak up for people who can’t speak for themselves.” She thought, “Who is talking and speaking for the trees? No one. I wasn’t prepared to accept what they were telling me. They were going to cut down trees that had taken nearly 200 years to grow.” She noticed that on the other side of Leather Lane, to the north, there were no ancient oaks. (HS2 says building on the north would have led to the loss of a different woodland area.) So she began campaigning to save the trees. With the help of her daughter, Blaize, she started a petition, which went on to amass nearly 43,000 signatures. O’Callaghan put leaflets through her neighbours’ doors. She also painted signs, and started a “toot your salute” campaign, urging local people to honk their horns when driving down the road if they wanted the oaks to stay. “You could hear people tooting all the way down the lane,” she says. “It was amazing.” “When I first met Carol-Anne at a meeting she organised to explain to locals what she was trying to achieve,” says her neighbour and nominator Victoria, “I saw someone passionate about giving a voice to those who don’t have one, someone not afraid of asking questions and calling out large, daunting businesses for doing the wrong thing.” The felling was due to start in March 2021. O’Callaghan invited residents to a socially distanced protest in her garden. Seventy people turned up. Workers took down three trees. “It was heartbreaking,” she says. “I couldn’t watch.” O’Callaghan made contact with the nonprofit Lawyers for Nature. “We discovered that seven species of bats were using the trees as a commuting corridor,” she says, “including the rare barbastelle bat.” Buckinghamshire Council got involved, and the felling was paused. So far just 12 trees have been taken down. “There are 87 trees still standing because of the campaign,” says O’Callaghan proudly. “But a further 20-30 trees remain under threat, as a final decision has yet to be made about the proposed over-road.” “We’re optimistic that they’ll hear our argument and take on board the ecology of the lane,” says O’Callaghan. “We want them to put in a green crossing in the gaps between trees, for the bats, and we’d like the place to become a conservation area.” An HS2 spokesperson said: “HS2 strives to reduce our impact on the environment, however some trees on Leather Lane are directly in the path of where the new railway will be built. From the outset, we have sought to reduce the number of trees that need to be removed, and across phase one we are planting up to 7m trees and will leave behind 30% more wildlife habitats than exist now. There is no evidence of bat roosts in the affected trees.” For O’Callaghan, campaigning for the trees has been life changing. “If you’d said to me 16 months ago that I would have this knowledge and understanding, and I’d be where I am now, I wouldn’t have believed you because I knew nothing about activism.” O’Callaghan’s request for her special treat is unusual: she wants to go ziplining, dressed as a bat. “It would be a way to express and promote everything I stand for in a completely ‘batty’ way,” she says. “I am called ‘Bat Woman’ by campaign colleagues now.” Hangloose Adventure Bluewater is happy to oblige, and one summer morning, O’Callaghan goes ziplining in a bat outfit and bat mask, along with a friend. “It was great,” she says. “But I hadn’t told anyone until I got there that I was scared of heights. So it was absolutely terrifying.” When she was on the zipline over the chalk cliffs and lakes, however, O’Callaghan’s worries disappeared. “It’s been a hard slog in the past 18 months,” she says, “so it was lovely to pay homage to the bats.” As she sailed through the air, O’Callaghan shouted: “For the trees and the bats – this is what we are fighting for!”