Turnworth, in Dorset, lies hidden away to the west of Blandford Forum and south of Sturminster Newton. The most recent estimate suggests that there are thirty inhabitants. In 1861, that figure was 150, ‘chiefly employed in agriculture’. Turnworth House, which must have given work to many, burned down in 1945. There’s no pub any longer, and no shop. The one surviving focus for the community is the parish church, St Mary’s. Built of flint, like dozens of others in the county, with stonework corners and strings to give added strength, it barely catches the eye. And there’s a gap on Google Street View where it should be.

Apparently unremarkable, the church turns out to be a gem. It owes its existence to Thomas Hardy. In 1869, with some ten years’ experience already as an architect, Hardy took charge of the restoration of the building. His work extended from reordering the layout to designing details, including the capitals of the pillars, which are intricately decorated with carvings of plants and animals – blackberries, sand lizards and even an owl.

Kester Rattenbury, a professor of architecture, writes about St Mary’s with enthusiasm and an expert eye. She notices how Hardy left the churchyard unlevelled and made room, beneath the west tower, for children, providing miniature pews for them. She extends comparable discernment and attention to Hardy’s other projects, notably his house, Max Gate.

Built in the 1880s, Max Gate has often been disparaged, sometimes as a vulgar and soulless suburban villa, sometimes as the physical embodiment of Hardy’s gloom. Rattenbury sees it as flawed, certainly, but inventive too, especially in its double staircase. Most of all, she praises the confidence of Hardy’s later extensions. The result was ‘never a pure, polished, perfect design,’ she writes, but rather ‘a writer’s house, continually occupied, always changing, imaginatively rich, perversely real’.

The Wessex Project is filled with similarly thoughtful and enriching descriptions of buildings – their meanings, histories and resonances. The chapter on Hardy’s later restoration of St Peter’s in West Knighton is especially perceptive and deeply felt. Nonetheless, Rattenbury’s focus really lies elsewhere. Hardy, she argues, was not simply an architect who became a writer; his writing is architectural throughout. His novels form an architectural ‘project’. Hardy’s use of writing, maps, sketches, drawings and photographs resembles an architect’s utilisation of multiple perspectives. Together, they create an equivalent to the imaginative projects, never realised but hugely influential, of Le Corbusier or Palladio.

So, as he developed Wessex, Hardy was thinking like an architect: imagining single buildings, their interrelations, their place within a landscape and the lives and communities they would serve. Alongside the works of fellow architects, such as Pugin, Street, Ferrey and Blomfield, he had John Ruskin’s The Stones of Venice in mind. Furthermore, Rattenbury suggests, his approach foreshadows modern practice – Rem Koolhaas’s Delirious New York, Bernard Tschumi’s ‘event architecture’, the activities of the Archigram group.

As a unifying idea for his novels, written separately over twenty years or so, Wessex has often been seen as little more than a marketing strategy, designed cunningly to please – and deceive – Hardy’s nostalgic readership. In Rattenbury’s account, it becomes an imaginative whole, always in view, in all areas of his output. In making this case, she proves in addition how powerfully important Hardy was as a conservationist and as a theorist of building conservation.

She especially praises his work on the church in West Knighton. Victorian restoration usually imposed order on muddle. A building that had gradually grown over the centuries, with many different styles jumbled together, would be given a single style. Modern taste, in fact, controlled what was called ‘restoration’. The 19th-century architect regularised and dominated the past. At West Knighton, however, there are no signs of Hardy’s hand; he devotes himself to the varied styles of the existing building and does not hide his repairs.

Rattenbury brilliantly compares this approach to Cedric Price’s ‘anti-architecture’. She also observes that the work was done while Hardy was writing his final novel, Jude the Obscure, that ‘bleak, unredeemed, horrific book’, as she calls it, which reveals ‘the oppressive use of buildings themselves to enforce social division’. Church restoration was one form in which that oppression took place. But all this, in Hardy’s sense of it, was nothing new.

Rattenbury is fond of the word ‘palimpsest’, using it to describe Hardy’s ideal of restoration, in which different, incompatible forms from the past continue to coexist, one laid on top of another. The palimpsest creates a ‘sense of continuum … carefully uncovered, reconstructed and made good’. This (influenced by her reliance on Simon Gatrell’s work) shapes her understanding of Hardy’s Wessex.

In the case of Hardy himself, though, this idea of continuum is more dubious. Each layer of the past contains a trace of conquest. Even vernacular architecture is not free of the will to power. Hardy grasped this so deeply because he was complicit in it. His activities at Turnworth marked the culmination of a decade in which his architectural work took him into the backwoods of Dorset. Rattenbury says surprisingly little about this period in his life, but it was crucial. With all his love of craftsmanship and his conscientious respect for ‘ancient buildings’ (however decayed), Hardy had been an agent of internal colonisation. He knew that what he took pride in, personally and with good reason, was how London asserted its power.

He was, moreover, as an architect, decisive and exacting. His father and brother worked for him on Max Gate but the former swore, afterwards, never to do so again. And Hardy, self-effacing though he was as a conservationist, saw value in self-assertion. His dog, a notoriously aggressive terrier, was called Wessex. Hardy had written on his gravestone ‘Fearless, Unflinching’. The epitaph’s near synonyms make a subtle distinction and a connection. Wessex, Hardy’s lifelong ‘project’, would never have come into being without courage and fierce determination.

Likewise, Jude the Obscure recognises that upwardly mobile aspiration is not only blocked by ‘the oppressive use of buildings’; it is also generated by their glory. Jude’s love of Oxford’s gothic is what kills him. But the ambition he feels is natural and admirable, as glorious as the gleaming spires that spur him on. Such dreams could only be realised for Hardy, however, in imagination – only in Wessex.