The Lighthouse Stevensons. Bella Bathurst

      The ferryman has a hangover. I have a hangover. At the hotel last night there was a wedding party which was topped off with a bar-wide debate on whether a man walking at three miles an hour down the deck of a ship travelling at 20 knots would, technically speaking, be doing 23 knots or 20 knots or 17 knots or actually not travelling across the surface of the earth at all. The left side of the bar argued that to arrive at a fair calculation, variables such as tide and current should be taken into account. The right half was trying to dance to Mariah Carey.

      It is 7 a.m. and the wind is already slapping at the sides of the jetty. The clouds are filthy grey, and the forecast says there’s a storm coming. The ferryman pulls the cord on the outboard and subsides into the stern, hood down. The boat cuts a raw white line across the Kyle of Durness, and I look out to the weather as a little blue yacht on the far side of the bay vanishes beneath a hill of water before re-emerging at its summit, hull almost clean of water. The Wrath in the Cape is drawn from the old Norse word for turning point, hvarf, but on a day like this there could be no more apt description, particularly since the MoD has turned the whole area into a live firing range. To me this already looks like the middle of a storm. Has the ferryman seen worse?

      He looks up. ‘Oh, for goodness’ sakes, yes.’

      The Northern Lighthouse Board’s Land Rover is waiting by the mooring on the other side, its windscreen wipers plinking. Wordlessly, the ferryman hands up a couple of boxes, hauls round and heads back in the direction of the bar. The Cape’s last Principal Keeper Iain Roberton has driven the 11 miles along the track partly to collect supplies and partly because he wants to get away from all the building works – people clumping in and out of the cottages, routine all over the place. This light is one of the last to be automated. As part of the process, the old diesel generators need to be removed and replaced with computerised monitoring equipment linked to the NLB’s HQ in Edinburgh. Where necessary the lighting apparatus itself has also been changed: big old lenses replaced with smaller modern alternatives, tungsten bulbs substituted for the first generation of LEDs.

      We pass a notice: London 746 Miles. Then a recent bomb crater. The MoD generally leave the keepers in peace, but once in a while pilots find the temptations of a large white tower pinned to a large stone coast overwhelming. The keepers haven’t been shot yet, but they do sometimes get lightly strafed. From the other direction there are different hazards: sea, wind, fog, all the things a lighthouse is designed to stand against. The buildings here are tight-fitted to this treeless, sheep-swept corner of the country, but there’s a cracked window pane in the kitchen from the last gale when the sea reached up 130 feet and tapped out the glass. The previous month a force nine lasted for four days (‘a bit breezy’), during which Iain had to make a grab for the railings to stop himself from going over the cliff. ‘It’s a right funny feeling being lifted off your feet. I lost my glasses, it was blowing that hard.

      ’The track broadens out to a wide green field, a tower topped with a black diamond lantern and one of the most astounding views in the world; two coasts, two oceans, and the eastward opening to the Pentland Firth. In the foreground a Bond helicopter is suspended just over the edge of the cliff, several reels of electrical cabling swinging from its underside. It has been picking up construction materials from the deck of the NLB ship Pharos in the Firth below and transferring them to the light. These are the last disrupted days before the changeover, the end of a profession, the removal men taking out one era and replacing it with the next.

      In November 1996, as the process of de-manning the Scottish lights was reaching its peak, I was 746 miles away on the third floor of the Science Museum. An exhibition of lighthouse optics had been set up and in a corner one of the old threeand-a-half-ton Fresnel lenses was revolving on its brass pivot with a low-watt bulb shining inside. I stood and watched it for a long time, entranced. If you looked directly towards the bulb it would vanish for a second and then reappear, LARGE and small, LARGE and small, its beam tinted with green or haloed with rainbows of prismatic light. If you turned towards the black partition wall, the same light swept round in a smooth circle, strongest in the centre but blurring out towards its edges. Its circuit was broken by three shutters interrupting the beam and making it appear to flash once, twice, three times. Then a long flash, then the same interruption: flash, flash, flash. Then round again, smooth and unperturbed, as sure of itself as any point of science could ever be.

      Below was a sign explaining that this particular lens had originally been used at one of the Scottish lights built by Robert Stevenson. I studied the sign for a while. Stevenson with a V, not a PH. A distant half-memory surfaced – hadn’t the writer Robert Louis Stevenson had some sort of connection with engineering or architecture?

      Downstairs in the shop I asked if they had any books on the Stevensons. They were helpful – looked up things on the microfiche, found plenty on Robert Stephenson, Rocket scientist, but drew a blank on lighthouses. There seemed to be nothing about the man who had made that light upstairs or how he might be connected to RLS. I walked across Hyde Park possessed by a single, idiotic idea. That lens was a piece of pure magic, as rational as anything the Scottish Enlightenment ever produced but as mythic as Prometheus. Those lights would be difficult to build even now, so how on earth had they managed it two centuries ago? Robert Stevenson – whoever he was – had obviously done something astounding, so why weren’t he and his family better known?

      That evening at home I picked through bits of RLS’s autobiographical writing – gleams of history in Kidnapped, forewords and introductions. It wasn’t just Robert who had been an engineer, I discovered, it was all of them, four generations, virtually every male in the family except for a couple of cousins and RLS himself. Though the Stevensons had been general engineers, they had stuck to lighthouses for so long that lighthouses had eventually stuck to them. That was who they were – Lighthouse Stevensons.

      Except, of course, for the one who wasn’t. Even in fragments RLS’s ambivalence was audible, sometimes directed at specific individuals and sometimes at – well, who? History? His peers? His wife, Fanny? Himself? My God, I thought, he writes so beautifully, and he sounds so torn. As you would be. If all your family – grandfather, two uncles, father, cousins – were firefighters or paramedics, if what they did was wild and pioneering and every day it made a difference to the lives of others, and if you then decided to turn aside from keeping people alive and become a writer, and if all your stories then ate the fame you knew was due to your family, you’d probably feel ambivalent, too. The more I read, the more astounding I found these four generations who had changed the shape of Scotland and then vanished, occluded by a brighter star. The following morning, I had decided. I might know nothing about engineering or the sea, but so what? I was going to write this.

      It was the first book I wrote, and I knew even then that I’d got lucky. It wasn’t just that I arrived at the point when the last of the Scottish lights were being automated, it was all of it. Sitting bowed in the basement of the Northern Lighthouse Board with an elephant folio of Cook’s Voyages splayed on the shelves, or sifting through boxes of Stevenson papers in the National Library of Scotland while the Edinburgh Festival rioted outside. For a few months I went every day. Something about the routine of it made it possible to build up a kind of retrospective intimacy with each Stevenson just through their handwriting – not just the words, but the words behind the words, the way they spoke and wrote: Robert by turns direct, commanding or circumlocutory, the way Alan’s hand could slip from health to sickness to seasickness, writing in bed or from the lighthouse yacht or from some forsaken end-of-the-road croft. Often his writing looks agonised, the drift of ink and its disorder reminding me of Robert Falcon Scott’s final journal entry from the Antarctic: ‘For God’s sake, look after our people.’ Occasionally, too ill even to hold a pen, he dictated through a scribe.

      Either way Alan was always more tempered than his father, more tolerant, but somehow further back. Robert was a master both of detail and of the grand design who worked to a hard view of human nature but remained thrilled by the lift of adventure. As RLS noted, ‘What he felt himself, he continued to attribute to all around him.’ RLS’s best known literary character is Jekyll/Hyde, still considered the ultimate delineation of a split personality: public and private, light and shadow, secret and revealed. His grandfather embodied all of those