Thirty five years ago I was teaching English (and Scottish) literature at the University of Tromsø in Norway.

On my first day, a woman offered me a lapel badge. It read "SKRIV NYNORSK" and was part of a regional campaign to allow students to write essays and sit examinations in Northern dialect rather than in "Bokmål", the "official" language. She pressed it on me, declaring that she knew for sure this was a liberty we Scots had enjoyed for decades. Alas, no. This review is written in English. For my generation, there is still a tiny displacement involved in reading prose – rather than dialogue – in Scots, as if, many centuries after St Augustine first saw Ambrose of Milan doing that remarkable thing of reading silently, it has to be acted out rather than simply read.

Lewis Grassic Gibbon went some way towards recreating prose fiction in which Doric was the language of the text rather than just of the rude mechanicals, but it wasn't until the largely urban fictions of James Kelman, Agnes Owens and Irvine Welsh – with Archie Hind, Alan Sharp and Alasdair Gray foreshadowing them in different ways – that literary Scots gained confidence, but again largely in city and contemporary settings where Scots is deeply threaded with other forms, notably Americanisms.

Begg's remarkable novel is couched entirely in Ayrshire Scots, with only occasional "lapses" into RP where appropriate. It is essentially the story – researched but fictionalised – of his own great-grandparents' lineage from the Covenanting martyr John Broun of Priesthill, "the Christian Carrier", through the "Killing Time", the "Ill Years" and the Jacobite spasm to the generation that survived long enough to see the best of its progeny killed at Vimy Ridge and Passchendaele.

The narrative is bookended with present-day reflections, presumably autobiographical to some degree. The author was a search-and-rescue doctor until his retirement and his unsentimental compassion and humanity shine through.

The book is largely set in the lands around Cumnock. It develops in relatively short chronological vignettes, focusing on individual characters and families, small farmers and farm servants, stonemasons, drovers, weavers and coal miners. My own ancestors came from those trades and that same place, though from further north, near Mauchline and Kilwinning (we number Weirs and Browns in our tree, which might make this a mite incestuous) but it is a more a measure of Begg's confident prose than of my ancestral dialect that I resorted to the glossary only four times, and one of those to check if a "heather-bleat" really was what I thought it was.

The Man's The Gowd For A' That is more than a linguistic tour de force or experiment. It is a powerful and sustained fiction, at times a little too much like the kind of animated history lesson beloved of mini-series producers. There are walk-ons by Robert Burns, who's on a branch of Begg's own family tree, and James Boswell, suitably sozzled, and while these are justified in context there are probably too many moments when characters come stage-front to explain the wider historical context. A cynic would say the morality is driven more by family loyalty than dramatic imperatives. Evil is something that exists beyond the hearth, in a snarling villain like Claverhouse. Begg's reimagined kin are rarely worse than venial, foolish or naïve. However, the book is brilliantly sustained. The use of Scots modulates consistently as he moves into more recent, industrial times, and those characters, for all their Walton-like simplicity and good cheer, find a place in the heart.