This summer the Pier Arts Centre in Stromness celebrates its 40th anniversary. The Orkney gallery, set up by Margaret Gardiner in 1979, contains key examples of works largely from the St. Ives School group of artists, delivered to this other artistic settlement by a sea some hundreds of miles north through the generosity and ingenuity of the woman who had purchased them. They take on a new resonance in Orkney, Pier Director Neil Firth once said, Gardiner's brilliance “to recognize that her collection of Modern British Art, gathered in from artists working under the heat of the Cornish sun, would hold an additional charge when viewed under a cooler Northern light.”

As part of the celebration, the permanent collection has been re-hung, with many new examples of art purchased in just over a decade since Gardiner's death in 2005, added to the collection, shedding a different light on the familiar pieces and extending the remit of the collection. There are works here by Sean Scully, Camilla Low, Oliafur Eliasson, a recently purchased Barbara Hepworth (Two Forms (Orkney)), to add to those already in the collection. There is also an insightful look into the architecture and interventions made for the first buildings pinpointed and purchased by Gardiner and friends in the community for the new art centre before its opening in 1979, and the subsequent new extension, which opened in 2007, after Gardiner's death in 2005. In another room, a series of posters charts early exhibitions at the Pier, an international line-up of Edward Munch, Picasso, Sidney Nolan, and more. It is impressive stuff, and as ever at Pier, part of the joy is in the contrast between the domestic scale of the buildings themselves and the international heft of the artists whose works hang on the walls.

Here, too, is an exhibition dedicated to Gardiner, an insight into the patron – if that is the right word for someone whose guiding principle was simply helping out her friends - filled with personal letters, with diary entries, with writings and even some of her own paintings. “She would be horrified to think that people would look at her painting!” Curator Andrew Parkinson tells me. “She certainly wouldn't have regarded herself as a painter. The pieces turned up after she died.” Gardiner, he tells me, had painting lessons from the abstract painter and St. Ives School artist Roger Hilton – who else would a woman in her position have painting lessons from, after all?

Gardiner, who was prominent in the anti-fascist movement and had, among many other remarkable things, helped people to escape from Nazi Europe as part of the movement For Intellectual Liberty, hated being called a collector, “for I never set out to collect,” she protested. Daughter of a prominent Egyptologist who had excavated alongside Howard Carter, she was ensured in her own private income by the investment activities of her grandfather, able to help out her artist friends by buying works from them when they were struggling. In the Hampstead of the 1930s, Gardiner found herself neighbours with Barbara Hepworth – who became a close, lifelong friend, and the subject of a fascinating biography written by Gardiner – Henry Moore, Ben Nicolson, and others fleeing from continental Europe in the face of war, such as Naum Gabo and Piet Mondrian. Her money helped them out, as did her humour and cooking, Parkinson tells me. “She was an open house for these people.”

After the war, when she moved – whilst still maintaining her Hampstead base – to St. Ives with Hepworth and Nicolson, she bought works from Alfred Wallis, Roger Hilton, Terry Frost and others of the school, who were often struggling to make ends meet.

She had “a genius for friendship”, as the artist Adrian Stokes once put it, and so, on her Hampstead walls, and now on those of the Pier, were arrayed the European avant-garde subsumed and interpreted in a peculiarly British fashion – a modernism of our shores, the brilliance of the work emerging from artists in the period just pre and post war. Compact and intimate, it suits a domestic scale – and the higgledy piggledy interiors of the Pier itself. The new exhibition takes many of her letters charting the gift of this collection and the setting up of the buildings themselves, in her lively manner, and there are photos, too, not least of Gardiner stripping the willow with the best of them up and down the galleries, on her 90th birthday.

In straightened times, when galleries like the Pier rely on sorely-stretched public funding and trusts for money to purchase new work, this celebration of a gallery resulting from an act of immense generosity, which changed and enhanced the thriving existing artistic landscape of Orkney, is a wonderful thing indeed.

THEN NOW WHEN: Celebrating 40 years of the Pier Arts Centre, Pier Arts Centre, 28-36 Victoria Street, Stromness, 01856 850209, 22 Apr – 9 Nov, Tues – Sat, 10.30am – 5pm

Don't Miss

This fascinating exhibition from photographer Roger Palmer is inspired by Scottish sailor Alexander Selkirk, who, in the early 18thcentury, was put off his ship in what appears to have been a misjudged battle of wills with his Captain, and lived alone on a Pacific island for four years, apparently inspiring Daniel Defoe to write Robinson Crusoe. Palmer's exploration of Selkirk and Crusoe combines fact and fiction, blurring boundaries in a juxtaposition of landscapes from Lower Largo (Selkirk's birthplace) to Isla Robinson Crusoe (then, Mas a Terra, where Selkirk was marooned), four miles off the Chilean coast, in photo, wall drawings and illustration.

Roger Palmer - Refugio: after Selkirk, after Crusoe, Kirkcaldy Galleries, War Memorial Gardens, Kirkcaldy, 583206 Until 23 Jun, Open daily - opening hours vary, see website

Critic's Choice

Alec Finlay explores the nature of place in philosophical mappings and chartings of the landscape, both physical and cultural. Whilst this exhibition brings together a number of his recent projects, its heart is in “gathering”, an ambitious creative mapping of the Gaelic landscape of the Highlands.

In essays, poems, photos, prints – including a new print created with Peacock Visual Arts – and maps, Finlay guides us to forgotten places in the Highland landscape; often inhabited, once, by wolves - often inhabited, once, by humans. Behind the pervasive grouse moors and deer stalking, there are shielings, the shelters of long gone summer pastures. There are ruined farms, springs, burns, glens, all modest, but all with their own meaning, the work as a whole finding its roots in Adam Watson's comprehensive modern guide to Gaelic placenames in the Cairngorms, The Place Names of Upper Deeside.

Finlay weaves in important ideas of rewilding and the right to care for the environment, vital in our current time of climate emergency. He creates a timeline of rewilding from the 18th century to the present day, made in collaboration with experts in the field.

Alongside this, other works of mapping created by Finlay in recent years - “a wolf among men a man among wolves” which looks at innovative woodland remediation in Mar Lodge, “humandwolves” at Trees for Life, Dundreggan and “Hutopianism” celebrating the hut and bothy culture, an installation at the Venice Architecture Biennale 2018.

Alec Finlay: Gathering, W OR M, Peacock Visual Arts, 11 Castle Street, Aberdeen, Until 18 May, Tues – Sat, 10am – 5pm