But periodically Mr Campbell, in beret, duffel coat and tartan tie, ventures up on deck. For today the weather is perfect: blue skies, dazzling sun and a breeze so light it barely ripples the water. Storms and gale- force winds are forecast, but for now, both Invernesshire's craggy coast and Rhum's magnificent mountains are sharply outlined.
Mr Campbell bought Canna - the smallest of this little cluster south of their big sister, Skye - in 1938, for pounds 9,000. In making the purchase his permanent home, he bucked the trend of the reviled absentee Scottish landlord; a tradition that began with clan chiefs of the 18th century who preferred a southern lifestyle and made paupers of the people back home, and today sees the foreign owner flying into his huge estate once a year for a spot of shooting and fishing.
Mr Campbell farmed Canna and tried to support its tiny indigenous population. He and his American-born wife, Margaret Fay Shaw, 92, won acclaim for their collections of traditional Hebridean songs and built up a formidable Gaelic archive and library. Ten years ago, after heart surgery, he gave Canna - population around 20, and now valued at pounds 500,000 - to the National Trust for Scotland.
"I had no heirs and I didn't want Canna kicked around like Eigg has been," he explains.
Born into the land-owning classes, Mr Campbell is none the less convinced that land should be owned by communities, not lairds, particularly when relations between the two are dire.
On Eigg, landowner-tenant relations have reached rock bottom. Its 60 or so residents (including 20 children) make it the most populated of the island quartet connected by the ferry. When the island's previous owner, Keith Schellenberg, a socialite and former Olympic bobsleigher, left the island for the last time last summer, he called in a mainland bobby for protection. The locals, a mix of indigenous families and "incomers", jeered him all the way to the pier.
But the long-running tale of feudal discord was far from over. For Eigg's new owner was Maruma, a "famous" German painter who bought the island for pounds 1.5m. Eight months later, Maruma - unknown, it transpires, in the art world - is at the centre of a fraud investigation and is reported to have put up Eigg as guarantee on a loan. Islanders are not even sure if he still owns it.
In the past year, Eigg has become a national cause celebre; a focus for discontent with Scotland's lairds and private land ownership which has created a clamour for sweeping land reform. Such is the height of the public mood that rattled landowners are meeting in Edinburgh today to counter the "high emotion and romanticism clouding the facts".
Eigg's own sorry saga began in 1975, when Mr Schellenberg bought the run-down and depopulated island for pounds 260,000. He arrived laden with promises of regeneration. Artists were drafted in as part of a tourist strategy. But by the late Eighties, islanders - some of whom were threatened with eviction from Schellenberg's tied properties - were accusing their new laird of neglect, arrogance and autocratic tendencies.
And it is Schellenberg, not Maruma, on whom collective local anger is still focused. Last week the islanders were still bitterly complaining that, as they struggled to eke out a living, Schellenberg entertained scores of chums to motorboat races and "champers and hamper" weekends.
His costumed Jacobite and Hanoverian mock battles did not go down well either. It may have been mere history to Schellenberg, but it was salt in the wounds of some locals. The1745 Jacobite rebellion and the final defeat of the clans at Culloden sounded the death knell for the ancient Highland way of life in which no one owned land, not even the clan chiefs - though they would later claim it as their private property. It also heralded the clearance of hundreds of thousands from Eigg and elsewhere to North America and lowland cities to make way for lucrative sheep farming.
"It wouldn't have been that bad if he had been looking after the place," says Davie Robertson, 30, who has lived on Eigg for a decade with his wife and two children. "But he wasn't, and it felt like he was rubbing our noses in it."
Schellenberg claimed that his tenants - who formed the Eigg Trust with the intention of buying the island - were "rotten, dangerous and barmy revolutionaries", more interested in smoking pot than growing crops. In the tense final months of his stay, his vintage Rolls-Royce was mysteriously destroyed by fire; the restive natives and even the Scottish National Liberation Army were suspects. When he finally got on the boat, local people threw a party to celebrate his departure, comparing it to the liberation of Haiti from Papa Doc Duvalier. "Schelly" is now the Big Bad Wolf of island children's stories.
Maruma raised eyebrows from the start. One day, the new owner dropped in by helicopter for a chat. Without as much as a blush, Maruma revealed that he had decided to buy Eigg after visiting the cave where 400 Macdonalds were burned to death by rival Macleods in the 16th century. "The cave is like a woman's birth canal," murmured the fleshy painter. "All the pain is there and yet so is the energy." It was then that a few islanders heard the first faint sound of alarm bells.
Today they are rudderless. Maruma has visited twice. The only sign of his brief influence is an enormous pile of crumpled car chassis, washing machines and tin drums gathered by the roadside as part of his Clean-up Eigg campaign.
"For all we know, we are owned by the bank now," complains Mr Robertson. "And all the time Eigg is being slowly strangled. What economic infrastructure there is is falling apart. There are grants to be had, but we cannot improve or do anything without the say of the landowner. Private ownership is a lottery, and unless the whole system is changed, this place will die."
It is a complaint that echoes throughout the region. At the nearby Knoydart estate, on a mainland peninsula just north of Mallaig, the landowner has changed four times in a decade. Fifty years after the legendary Seven Men of Knoydart launched Scotland's last illegal land grab, the tenants - all incomers, for the indigenous population has long since disappeared - have also formed a trust with the long-term aim of gaining control of the land.
Nigel Hawkings, Knoydart trustee, laments the instability for communities inherent in the current system. You have to jump through hoops to buy a croft and half a dozen acres, he points out. "But if you want to buy a 50,000-acre estate, there is no vetting at all."
The Highlands and Islands are awesomely beautiful, but the terrain is austere and unforgiving. Living off the land is a raw experience. The drama on Eigg has tended to obscure hard facts. Eigg has no township or village centre. Its homes and crofts are strung out and isolated, occasionally grouped in threes. There are few community facilities and no pub; old men share a nip in parked cars. Socialising centres on the only shop - in reality no more than a shed - and, on the long, dark winter nights, on neighbours' houses.
Scraping a living is hard enough, reformers argue, without the vagaries of landowners, who wield enormous power over accommodation and jobs. In Eigg, families can only circumvent the laird's grip on property and land by persuading the few with crofting rights to let them site a caravan on their land while they wait - up to two decades in some cases - for a permanent solution. Over the past 100 years, crofters have secured agricultural land rights which are protected in law and passed from generation to generation; they have a security of tenure that tenants - who are in the majority on Eigg - do not enjoy.
In summer, up to 160 people a day visit, mainly bound for the island's Singing Sands. "The beach squeaks, actually," confides Mr Robertson. "But the tourists expect four verses of 'Flower of Scotland'." What employment there is is seasonal, and in winter the pervading whiff of decay, poverty and neglect finally overpowers. This is the land of ramshackle cars, the last stop from the knacker's yard for vehicles that fail the mainland MOT. With no mains electricity or water supply, only the lucky have generators and some still draw water from outside burns. Maruma was shocked to discover that damp and disrepair forced Dolly Ferguson, 83, to live, eat and sleep in one room of her island home. He had promised her a new house before any work was done on his own. She is waiting.
While Maruma's manor house lies empty, the handful of pensioners still living on Eigg pray that the long-promised sheltered housing - delayed by discord - will be complete before their own health fails. Old Morag is the latest to be shipped off to a home in Fort William. In the dilapidated community hall, volunteers wade through inches of rainwater in the leaking kitchen to cook and serve pensioners their weekly lunch. Land for a desperately needed new hall is in the gift of the laird. Negotiations have been going on for years.
Among the old, there is bitterness against the successors to Lord Runciman, Eigg's "Golden Age" custodian in the first half of this century.
"What would I do? I'd get rid of the whole bloody lot of them," says Angus MacKinnon, descendant of the island's Gaelic bards. But despite disenchantment with modern lairds, a yearning for the benign lord and master persists.
"Lord Runciman was rich, you see, and so could afford to run it as an interest," says Mr Mackinnon. "It didn't have to make money. Everything was spick and span and everyone got a job when they left school."
Could the community do that for itself? His eyes narrow. "I can't see how they would raise the money."
In his Edinburgh University study, the human ecology lecturer Alistair McIntosh, a founder of the Eigg Trust, argues that Highlanders like Mr Mackinnon suffer a lack of confidence born of three centuries of "cultural trauma". He compares them with the descendants of Native Americans driven off the land and herded on to reservations. Mr McIntosh, from the Outer Hebrides, believes that only when they regain control of their land will Highlanders recover.
Dismissing private landowners as "parasites", he laments the Eigg Trust's failure so far to buy the island. But he is hopeful. "If you raised the issue of land ownership five years ago, no one could see why it was a problem. Now a benign landlord would not be seen as enough. We are not talking nationalisation but community control."
For signs of change he points to the Assynt estate in Sutherland and the historic 1993 buy-out by local crofters of their absentee Scandinavian owner. The model has already been successfully emulated on Skye.
Many more crofter takeovers may now follow after a surprise offer from Michael Forsyth, the Scottish Secretary, to sell or give away - reformers argue "give back" - government-owned land to crofters' trusts. Mr Forsyth has suggested that private landowners might like to follow his example. Suddenly crofters' power - whose champions were once dismissed as Communists and dreamers - equals popular politics.
While Assynt's crofters had a century of hard-won agricultural land rights to fall back on, Eigg, with just nine crofts, faces a tougher task. But if it wins, it will present a far greater challenge to the current system because other non-crofting communities could follow suit.
Reformers insist that community ownership would revitalise the Highlands and Islands; they hold up Norway as an example of a country whose restrictions on who can own land and how much they can purchase have created a vibrant economy in similarly remote and difficult terrain.
The land issue, Mr McIntosh believes, is inextricably linked to Scottish devolution or independence. But he recognises the danger of racial prejudice. His definition of a Highlander includes anyone who "nurtures and is nurtured by the land". Thus there is room both for Mr Robertson, weaned on his Highland grandmother's tales of evictions by heartless lairds and driven to right past wrongs, and incomers such as Sue Kirk, married to the local shepherd, and Maggie Fyfe, who are essentially concerned with creating a community that has something to offer their children. Incomers and natives can sometimes clash, but here they might yet prove a potent combined force.
Frank Rennie, past president of the Scottish Crofters Union, says he cannot remember a time in his life when Scottish land reform has been so topical or supported by such a range of diverse organisations and "unlikely allies." The Crofters Commission, a regulatory body, believes that Mr Forsyth's offer has the potential to "inject new life into some of the most remote and fragile parts of the Highlands and Islands".
Leading lights in the crofters movement are urging their members to seize the moment - not just for themselves, but for the sake of future generations.Reuse content