After George Mackay Brown died in April 1996, an obituarist testified that the poet had been “anything but gregarious”. There followed the tale of a craftsman's solitude, writing from 9am to 1pm at his kitchen table six days in seven, and of a deterrent note pinned to the door of his former council flat in Stromness: “Working all day”.

The image was tenacious. Brown and his Orkney islands were of a piece: remote, detached, stoical, attuned to myth, history and the weather. Yet as islanders sometimes remind you, the archipelago hardly counts as remote to those who live there. The real man stood in a similar relation, it seems, to his work and his overlapping networks of friends.

The tale of the pinned note is deceptive, in any case. Someone who is “anything but gregarious” does not need to fend off visitors. That's a task for an individual balancing the demands of work with an appetite for company. In Joanna Ramsey's memoir the traffic to Brown's fireside is constant. In this account, his life was full of welcomed guests, his “solitude” a half-truth. The poet was introverted and sometimes afflicted by depression, but he was no recluse.

He measured the world by his art. “Orkney writer” though he was, first and last, it was not a small world. Though he did not travel often or far after returning from post-graduate studies in Edinburgh in the early 1960s, Brown had a vast aesthetic and moral map in his head. As the poem Places To Visit, written around that time, concludes, “Thorfinn, you will learn more in Orkney/ Than Mansie did/ Who made seven salt circles of the globe”.

Brown believed it and lived accordingly. Stromness contains just a couple of thousand people, but for him they represented all. The writer ranged, in any case, though both time and space. In his private life, he was in no sense confined. Some of his friendships were lifelong. Some depended on the freemasonry of art. Some qualified as solemn emotional contracts (or “affairs”). Several relationships managed to be both intense and accidental, as though fated.

Joanna Ramsey's story occupies the last of those categories. In larger accounts of Brown's life and work, it would hardly count – if it counted at all – as a footnote. The poet himself saw no need to mention it or her when, towards the end, he wrote an appendix to his 1985 autobiography For The Islands I Sing. But then, with the blunt dismissal “There is nothing much to add” he contrived to overlook other friends, “muses”, former lovers, “hordes of visitors”, helpers and relatives “who see to it that I don't starve”.

Brown might have been striking a pose; he might have been expressing the essence of his existence as he understood it. Nevertheless, in 1993 Ramsey discovered she had “no place there” – the appendix – “at all”, despite being the recipient of affectionate acrostic verses, and despite a lovely work written for her new-born daughter, one that made it all the way to Brown's Collected Poems. So what was Joanna Ramsey to him, and he to her?

The second part of the question is easier to answer than the first. For the eight years of their relationship, the last eight years of Brown's life, the poet was – it is fair to say – everything to Ramsey, yet she struggles to define the reasons. In one sense, the attempt to puzzle out an explanation is her memoir's purpose. It is as much the story of Joanna Ramsey as she searches for a place in the world as it is the tale of Brown's last years.

She was 35 when first they met in 1988; he must have been 67. Theirs was not – though the superfluous explanation comes late in the book – a sexual relationship. Nor was it, at least to begin with, a bond between artist and acolyte. Ramsey, as she makes abundantly clear, was meanwhile just one of several women contending – the word will have to do – for Brown's attention.

Perhaps the best way to put it is that for long periods he and Orkney provided the solid centre that London (and much else) had been unable to provide. She came to know his work as she came to know him, but their friendship seems to have been born as a spontaneous, natural event. It had, as these things do, its ups and downs, its intimacies and evasions. On this telling, it mattered to Brown, but it was crucial to Ramsey.

There are no disquisitions on the poet's creative process in the memoir, no piercing insights into his character. Instead, the book offers a slowly evolving portrait of a man who managed to be sociable and private, friendly yet ever guarded. Even to his friends, Brown did not truly give much away. The Seed Beneath The Snow makes you wonder if he was capable of such a thing.

Ramsey, relying heavily on diaries, constructs a subtle portrait from a mundane round of social events, hospital visits, arrivals and departures, evenings in and days out. Her story affirms the image of Brown as the insular stoic and, with deft touches, destroys that image. He was human, foolish, fond and frail.

He was also, to his friend, a kind of living poem. In several glowing, loving passages she honours art and artist alike.