Postcard from ... Tresco

Artist Anthony Garratt springs on to the wall above the small harbour, gazes down at his artwork lying on the honey-coloured sand, and sighs. “It’s too sunny, too optimistic, I need to free it up.” Minutes later, his soft-focus depiction of a neighbouring island is overlaid with fresh splatters, dribbles and slashes of paint: an expressionist weather front exploding out of the canvas.

This week Garratt completed his fourth huge landscape, each displayed outdoors, where it was created over a two-week period; together they transform Tresco into a sort of giant al fresco gallery. One of five inhabited islands in the 150-strong archipelago of the Isles of Scilly, 28 miles west of Cornwall, Tresco will exhibit the art works, kissed by sun, flecked by sea spray and caressed by Atlantic wind, until late September.

The Bristol-based artist’s three other acrylic and oil paintings will adorn a pristine beach, an inland hill gazing towards outlying islands, and Tresco’s botanical gem, the Abbey Garden. As well as reaching a wider audience than in a gallery, he believes the exhibition in the unsanitised great outdoors will provide “far more immersive, thought-provoking” viewing.

“By exhibiting the paintings in the place they were painted, island visitors will each have their own personal experience with the creations,” he says. “The painting’s appearance will change as the light and weather shifts around them.”

To ensure his al fresco display can withstand the island’s potentially dramatic Atlantic fronts, the artist employed an architect, structural engineer and two shipbuilders to produce the sturdy steel easels supporting each work. Each of the 2.5m by 2m paintings has been treated with a protective varnish.

The unique exhibits are the latest chapter in Tresco’s rich artistic history. Creative figures have long drawn inspiration from the small island’s extraordinary diversity, from its wild craggy north, rolling central meadows and dazzling southern beaches, alongside the Abbey Garden’s Mediterranean flora.

“Painters also get addicted to its incredibly clear, constantly changing light,” says 34-year-old Garratt.

Yet it’s still surprising to find so many acclaimed works of British art from the late 19th and 20th centuries dotted liberally throughout Tresco’s restaurants, public spaces and rental cottages. The Tresco Art Collection, driven by the passion of the island’s owner Robert Dorrien-Smith and his wife Lucy, started with artists connected to the region, and also embraces works of colourful flora. Since the early 1990s they have offered residencies to up-and-coming artists, including Garratt, who exhibit their works in the small but respected Gallery Tresco.

“We don’t advertise ourselves as an art destination,” says Dorrien-Smith as we sit in his office underneath a painting by Ivon Hitchens. “Guests gradually absorb the message. It’s very gratifying when they appreciate Tresco’s art and write to me about works they’ve seen here.”

I don’t need to travel far to start absorbing. My seafront rental cottage sports a delicate pastel-hued beach scene by Rose Hilton, and a five-minute cycle ride reveals a superb display at Tresco’s Flying Boat Restaurant, including paintings by Alfred Wallis, Graham Sutherland and Harold Harvey, alongside those of Sir Terry Frost and Dame Laura Knight.

A short ferry ride takes me to Bryher island where the Dorrien-Smiths bought and redeveloped Hell Bay Hotel as another showcase for the collection, including works by Ivon Hitchens, Dame Barbara Hepworth, Sir Matthew Smith, Patrick Heron, Roger Hilton, Hugo Grenville and Richard Pearce.

But perhaps the most memorable location is back on Tresco in the Abbey Garden. Among the Australian fountain palms, South African protea and Californian cypress are Tom Leaper’s shiny balancing cube, and David Wynne’s two sculptures “Tresco Children” and “Gaia”, the latter carved out of marble given to him by Beatle George Harrison.

They will soon be joined, albeit temporarily, by Garratt’s latest landscape. The painter hopes it will be the first of many exhibitions of works shown in situ around the UK, and is already developing the idea of an exhibition rising from London’s muddy Thames shoreline. “I’d also like to do one in Cornwall’s Eden Project, which you stumble across in the foliage. I have too many ideas, not enough time.”

Ian Belcher was a guest of Tresco Estate (tresco.co.uk). Its Sea Garden Cottages sleeping six cost from £1,615 per week; one-bedroom cottages for two cost from £160 per night. Skybus (islesofscilly-travel.co.uk) fly to neighbouring St Mary’s from Land’s End and Newquay from £140 return, and from Exeter from £255 return