It was Tuesday, March 31, 1998 and, at Fair Isle South and with something of a lump in his throat, as dawn rose and the sky silvered, Bill Gault, 62, dimmed the lamp for the last time.

The flag was lowered, as a few guests – not least the Princess Royal – looked on and, just like that, Scotland’s age of manned lighthouses was over.

Every last of the 208 lights for which the Northern Lighthouse Board (NLB) was responsible had now been automated. Monitored remotely from an adapted Georgian townhouse at 84 George Street, Edinburgh.

The technology for unmanned automated lights had been around as early as 1894 – but it was only from 1960 that serious modernisation began.

Even then, quite a few lighthouses had to be crewed for many more years. Some had to file round-the-clock weather reports; some had foghorns and radio beacons that, too, required a human presence.

Life on a lighthouse was not for sissies. Three men, closely confined, in spartan conditions for four to six weeks at a time.

Each taking an eight-hour shift, on his own, in turn. On duty, you were not allowed to read. You were not even allowed to sit down. You had regularly to crank up the winding-gear, a system of weights and chains that kept that great light turning.

It ticked relentlessly. The light itself kept perfectly bright; the ‘optic’ – great lenses magnifying the ray many times – spotless. And the light had to stay at all times ‘in signature’.

Princess Anne’s visit to Tiumpan Head in 1956 kindled her lifelong adoration of lighthouses

Tiumpan Head, the nearest major light, flares white – twice, in fast succession – every 15 seconds

Every lighthouse has a unique character, to use another word. The Butt of Lewis tower, for instance, flashes white every five seconds.

Tiumpan Head, the nearest major light, flares white – twice, in fast succession – every 15 seconds. (It was, incidentally, a royal visit to Tiumpan Head in 1956, when Princess Anne was just six, that kindled her lifelong adoration of lighthouses. She has been Patron of the NLB since 1993.)

Even when you were not on watch, you still had to do your share of cleaning, cooking and maintenance. Empty the bucket that was the only available sanitation.

Venture outside – if you could – watching your footing. If you needed any reminder that cliffs, slippery stone and steep steps are dangerous, the store of every lighthouse included – lodged discreetly in the rafters – coffin-boards.

And hope, when the day came for relief and shore-leave, some weeks with your family and a break from that ceaseless ticking and life in round rooms, the weather would be kind enough to let you off.

On the odd, dread occasion, you would have to tell the master of the NLB vessel coming into view that ‘There is no landing’, as the wind howled and the sea washed white around you – and that was you stuck for another few weeks.

All lighthousemen coveted a shore station. Somewhere on the mainland, or at least on an island big enough to give you the chance of a walk. Where the senior keeper might even be able to live with his family.

Rock stations, where such exercise was impossible – the likes of Skerryvore, or Bell Rock – had the distinct feel of a prison. This was a setting – claustrophobic; sweaty – where men could go mad. Or merely criminal.

And on occasion did. On August 18, 1960, Hugh Clark, an elderly assistant keeper, was shot dead in his sleep at Little Ross Island lighthouse, just south of Kirkcudbright – by another assistant keeper, Robert Dickson.

Before he had a chance to dispose of the body, though, Dickson was surprised by unexpected visitors, and fled. There was a nationwide manhunt before he was cornered in Yorkshire – and he was most fortunate not to hang.

And when the light went out on the Flannan Isles, in 1900, west of Lewis, and shocked investigators could find no trace of any of the three keepers, some maintain that one of them must have gone berserk, killed his comrades and then thrown them – and himself – off a cliff.

The real mystery is that a cardinal rule was broken: one man had to remain in the lighthouse at all times.

Always, that air of discipline and duty. Fall asleep while you were on watch, and that occasioned instant dismissal.

In December 1864, the revolving light mechanism at the newly built Monach Isles lighthouse, on wee Shillay off the North Uist coast, jammed and failed. In the pre-Marconi era, there was no way of summoning assistance and an engineer.

Did the men sit on their hands and bemoan their lot? No. For 17 nights, each in his turn, the keepers rotated it by hand. Continuously, through long midwinter dark. And kept it in perfect signature.

Jeri Cormack is the youngest lighthouse keeper in the UK

Monarch has an interesting, slightly dark history. In 1936, two keepers drowned when their boat was overwhelmed as they tried to row back after collecting mail and supplies.

They were last seen standing on a tidal rock. Three weeks passed before the sea surrendered the bodies of Principal Keeper Milne and Assistant Keeper Black.

In 1942, the Monach lighthouse was decommissioned. Stood for decades dark and derelict.

And then, in an astonishing comeback – after the 1993 Braer disaster at Shetland, the authorities feared similar oily horror by the Western Isles – the NLB decided to build a new lighthouse on Shillay.

It opened in 1997, but was not tall enough. Visible from just ten miles out; the ideal is 18. The authorities took stock and decided to recommission the 1864 original. Equipped with the latest technology, it has blazed anew since 2008.

The day of stationed lighthouse keepers is long past. But it is not widely known that we still have retained lighthouse keepers in Scotland. Seventeen of them. And the youngest – indeed, the youngest in all the UK – is Jeri Cormack, 28, in the far north of Scotland.

It is only a part-time job, but Jeri is responsible for three lighthouses – Noss Head, Dunnet Head and Duncansby Head – and gives each of them a full day’s love once a month.

She has a big checklist to go through. Looks about externally for any damage by wind, weather or criminality. Gathers away any litter.

And Jeri has to do a lot of cleaning. Especially of the windows on the lantern-deck, the ones that matter most. If left to become grubby, the visibility of the light can be reduced by several miles.

After all that, of course, she sends her reports to 84 George Street. ‘You’re in such a fantastic place, you’ve got views like this,’ says Jeri proudly, ‘and it’s history that’s still relevant.

‘It’s still doing the same job it did, two hundred years later.’