Ihave come across many ways of securing thatch to a roof, from pointed hazel spars to heather rope, iron crooks to old-fashioned tarred twine. But this 17th-century roof in the fishing village of Ardersier offers something I haven’t seen before: everything has been tied down with orange baler twine. As basic as the technique may seem, it’s worked: the string-tied water reed has survived 35 winters in the north-eastern Highlands. The thatch is underpinned by a base coat – a layer of turf resting on the roof timbers. The turf is probably over a century old, and flecked with heather and marram grass (known here as “bent”). Once, sand dunes lined the coast of the firth, providing marram for more than 300 thatched roofs in Ardersier. The sand dunes are now gone, and the cottage I’m working on is the last thatch in the village. Things were different in the village’s marram grass heyday. “Folk just helped each other do the thatching,” the owner of the house I’m working on, Graham Walker, remembers. Maintenance was done annually, by the villagers themselves, using whatever materials were to hand. In the Highlands, there was no equivalent of the English master thatcher, a specialist who devotes a lifetime to one craft alone. When Graham’s roof was last thatched, 35 years ago, that self-sufficient way of working had vanished, and the nearest available thatcher lived in the western Highlands. Now, Scottish thatchers are in even shorter supply: the thatcher Neil Nicholson has boarded a CalMac ferry from North Uist, in the Outer Hebrides, and I have driven here from south Devon. But Graham, a retired gravedigger for the Highland council, continues some of the old ways of doing things. He joins us daily on the scaffold, carrying reed, removing old thatch and tidying up. He’s the most hands-on and helpful homeowner I’ve met in my 12 years working on roofs. With the last section of roof stripped to reveal another snaggle of orange twine, we leave Graham organising the tarpaulins and head back to the cottage we are staying in, a few miles away. Driving west along the coast road, windows down, clouds of turf-dust swirl off my forearms, and the cab fills with the almond scent of gorse. Country diary is on Twitter at @gdncountrydiary Tom’s book about his life as a thatcher, On the Roof, is out on 29 August and available to preorder now