Crossing From Dorlin Pier On The Mainland, I watch an oystercatcher skim the water of Loch Moidart, a narrow inlet on the west coast of Scotland. We pass the imposing silhouette of Castle Tioram, a medieval ruin that was once a staging post for the mighty Clan Ranald, its turrets still intact. To the east is the peak of Rois-Bheinn; to the west, the islands of Muck, Eigg and Rum, and north is Skye It is surely one of Scotland’s most striking locations. We tie up at the wooden jetty; there are kayaks and a rowboat bobbing in the bay. I look up the manicured lawn towards a grand 18th-century house in textured local stone, with a cascading row of Scottish gables and a facade by Sir Robert Lorimer, who designed much of the city of Edinburgh, including the New Town and The Scottish National War Memorial.

The owners of this private-island hideaway are Robert Devereux, the former chairman of the Frieze Art Fair who now runs the African Art Trust, and Vanessa Branson, sister of entrepreneur Sir Richard. She has her own enterprising streak too. Her contemporary art space, The Vanessa Devereux Gallery in Notting Hill, was credited with showcasing artists such as South African William Kentridge for the very first time. She also set up the Marrakech Biennale more than 10 years ago and co-founded the much-loved El Fenn hotel in the heart of the medina, which has a concept store selling Fez pottery and vintage-style clothes, and a four-bedroom private riad that can be hired in its entirety.

And now they are opening up their Scottish holiday home. ‘I spent 20 years watching my children enjoy this playground of infinite possibilities, seeing my friends experience a profound sense of peace away from cats and the hum of the city,’ Branson tells me. Eilean Shona has a notable history of former residents. It was the wedding present to Lady Howard de Walden from her husband-to-be; before that it was home to the seafaring Captain Swinburne, an acclaimed collector of rare and beautiful pine trees, which he planted all over the island. Since 1995 it has been in the hands of the Branson-Devereux family. The main house has 11 bedrooms, and the Edwardian dining table seats 20.

It is very much a classic Scottish family home but it can surprise with, for example, kilims beside tartan, and a powerful collection of modern paintings and photographs on the walls, including a specially commissioned mural with bold colours and geometric patterns.

The billiard room and library are redolent of Victorian pastimes: cues lined up neatly in a casket; volumes by Shakespeare, DH Lawrence and Romantic poets on the shelves beside Martha Gellhorn and an illustrated book on African ceremonies. The traditional palette is strong: claret, emerald and violet, and much of the furniture is Georgian and Regency. Yet in a tall alcove halfway down the stairs, I pass a voluptuous wooden sculpture from Burkina Faso. In the bedroom facing west is a special commission by Catalan sculptor Pep Duran, who has carved a kingfisher’s nest into the polished-birchwood headboard.

There are seven Hebridean croft cottages on the grounds, each built from local stone. The Old School House sits back from a secluded bay, a thread of smoke rising from double chimneys; it’s a favourite spot of Kate Winslet, who is married to Vanessa’s nephew Ned Rocknroll. Red Cottage is on a slope beside Captain Swinburne’s magnificent pine forest. Tioram Cottage reminds me of family homes in old-fashioned children’s stories. There is also an artist’s studio by the shore, where Branson and her 26-year-old daughter Ho, an artist, astrologer and curator, while away afternoons painting Loch Moidart with grey herons and white-tailed eagles swooping across the sky and over the fells of the Western Isles.

‘As the sun goes down we take a bottle of Chablis and smoked-salmon sandwiches, and watch the otters frolic with their young/ Branson says, smiling. ‘We might spot a rare seabird overhead in the last of the light. We once saw Halley’s comet reflected in the loch, stats completely surrounding it. You feel so connected to nature here.’ The island serves as the destination for the annual Branson clan’s gathering of children, siblings, nephews and nieces, ‘We swim from the jetty every morning,’ Branson says. ‘It’s freezing, but you feel invigorated for the rest of the day.’ They hike or kayak to Shoe Bay, a pocket of fine white sand, arriving to delicious mussels or venison sausages brought across by the island’s staff and cooked on the campfire.

There they play beach games: frisbee, petanque, bat tennis. ‘I might pick up the guitar and we’d all sing along, or perhaps we would go for another swim, climb rocks beside the water and catch a glimpse of seals in their colony – and before you know it, it’s 10 o’clock at night.’ When I discover JM Barrie is thought to have written the screenplay to Peter Pan while holidaying here, it starts to make sense. Eilean Shona does somehow feel like a Neverland with all the childhood magic of deep, dark woods, rock pools, sand castles, crabbing and picnics among springy heather. ‘We are custodians,’ Branson tells me softly, ‘and we are lucky enough to be caring for the island for the time that we are here’.