When Tim Smit and John Willis first came across The Lost Gardens of Heligan in 1990, the land belonged to brambles – a great, twisting mass of spiky tendrils, each groping out to claim any buildings or open space within their vicinity. Trees had sprouted up from the glasshouse. Ferns had emerged in great Jurassic clumps. The local wildlife was tangibly thrilled – nature had claimed the garden back for itself.