On Wednesday evening, as the light was fading, I stood chatting under a London plane tree to Marcus Carambola, who was about to spend his 50th consecutive night sleeping in a hammock among the tree’s branches, 10m above the pavement. Carambola, barefoot, 33, spoke of the tree as an old friend: “We have got to know each other pretty well,” he said, looking up. The 120-year-old tree, in Oakfield Road, in Haringey, north London, has become the emblem of a battle between residents, insurers and the local council that has implications for leafy streets across the country. The owners of the two neighbouring houses, part of a Victorian terrace, have for the past 10 years been engaged in a life-sapping battle with their respective insurers, Aviva and Allianz, over the insurers’ responsibility to pay for underpinning and repair work caused by subsidence. The bills run to £400,000. A couple of years ago, the insurers apparently spotted a new way to avoid this payout: they raised, with scant evidence, the idea that the plane tree – though pollarded each year by the council – was the sole cause of the problem and sought to shift liability for repair to Haringey. If the council removed the tree, they argued, underpinning would not have to be done, because the issue – despite the drying climate and clay soils – would magically go away. The council took the path of least resistance. Two previous attempts to cut down the tree have been thwarted by protesters. The latest is set for tomorrow. Carambola, meanwhile, has been training locals, the youngest 18, the oldest 72, to take his place in the hammock so that the vigil can carry on and alternative remedies be found. “If this one goes,” he suggests, “all the trees you can see, and hundreds more are also under threat.” The campaign is linked to others across the country. He plans to be still up in his hammock in 50 days’ time. Gospel truths I once had a long, mostly enjoyable doorstep conversation with a pair of Jehovah’s Witnesses that began with me suggesting that there was more useful wisdom in Shakespeare than in the collected books of their Old Testament. It ended with us trading quotes from our respective gospels, them giving me “thou shalt nots”, me making the case that they were “such stuff that dreams are made on”. A couple of things reminded me of that conversation last week. The first was the news that Sheffield Hallam university was closing its English literature course in light of the government concentrating funding on “useful” degrees. Conservative voices have always wanted to limit access to the humanities; they spread the word about doubt and empathy and dissent. The second, blunter, reminder of my doorstep standoff was a banner in the Roe v Wade protests: “I’m not part of your book group,” the banner read. “I don’t give a fuck what the Bible says.” Answers on a postcard I’m in a weekly pub quiz team that is sometimes radically improved by Shaun Wallace, the most formidable of quizzers on ITV’s The Chase. Shaun’s day job is as a criminal barrister, and in the past week he has been on the picket line at the Old Bailey. The dispute, he says, is a no-brainer. Junior legal aid lawyers get paid about the same now as when he started out in the profession more than 30 years ago. You don’t have to be a Mastermind champion (2004 for Wallace, special subject FA Cup finals) to know that very different answers are required. Tim Adams is an Observer columnist