To many people, Shelter and the Campaign to Protect Rural England must seem like unlikely bedfellows. Shelter is typically associated with strident demands for more new homes to help hard-pressed city-dwellers facing homelessness. CPRE attracts almost the opposite caricature: that of the genteel campaign for well-off NIMBYs determined to preserve their corner of rural affluence. When I first met Shaun Spiers, not long after he’d taken the helm at CPRE, I asked him what had drawn him to the role, and was genuinely taken aback when he said it was because he’d always been an environmentalist. From my London-centric, housing obsessive viewpoint I had never thought of CPRE as an environmental campaign.

It’s not hard to see where these stereotypes come from. Shelter is indeed preoccupied with the desperate lack of homes that underpins our mounting homelessness crisis. And CPRE members have indeed fought many a battle against new homes being built, up and down the country. Campaigning is hard, and often thankless work. The experience of fighting powerful vested interests, remote governments, stifling bureaucracies and sheer public indifference can be draining. It encourages campaigners to take clearer, simpler positions that might just get some attention. But taking strong positions tends to mean saying no to things, and defining the other side as the enemy. The longer campaigns go on, the deeper those divisions grow – feeding negative stereotypes and encouraging further retrenchment on both sides.

I’ve met liberal economists who think the abolition of all planning controls would deliver utopian outcomes for everyone. And I’ve encountered Green Belt campaigners who insist that a derelict petrol station on a main road in inner London must not be redeveloped for social housing, because it happened to be classified as Green Belt. It’s easy to deride this as narrow intransigence – and to be honest I’ve done just that at times. But their argument was not that this old petrol station – minutes from a tube station and next to a 20-storey tower block – was an invaluable ecological treasure, or even that it was doing anyone any good in its current state. It was that if they accepted a redrawing of the Green Belt boundary in this case, there would be no end to it.