You may (or may not) already know this, but researching the long 18th century in 2023 is rarely a life-affirming, paradigm-shifting conversation over wine with Plato in the groves of academe. It is seldom, even, a couple of tins of warm lager on the train home after guesting on an episode of Start the Week. It is sometimes, though, sitting in an archive transcribing the traces of long-vanished lives, conscious of the passing of time, quietly excited but still wondering if any of this actually matters, whether the partial recovery of someone else’s life really is the fullest way of living your own.

Reading Ian Marchant’s deeply moving new book involves the realisation that the excavation of the past can indeed be among the most pleasurable and purposeful ways of finding meaning in the present. This awareness is especially urgent for Marchant, since, in January 2020, shortly before the announcement of the first coronavirus case in the UK, he was diagnosed with incurable prostate cancer. Around this time, too, he discovered that he had an 18th-century ancestor who had kept a diary for 14 years. Unsure about how long he had left, Marchant sought relief from the rounds of chemo in the investigation of how one of his forebears had measured out his days.

Thomas Marchant (1676-1728) was a well-connected, prosperous Sussex farmer, who recorded his household and parochial business and the ways in which he spent his leisure time (including prodigious bouts of drinking and punishing hangovers) in a diary between 1714 and 1728. Edited by Anthony Bower, it was published by the Hurst History Study Group in 2005. It is mainly known to 18th-century specialists as a key document in the history of cricket, and by extension the recreation of the rural English ‘middling sort’, since Marchant regularly recorded (in extremely spare terms, it must be said) his son Will turning out for the parish team.

If Marchant was no John Arlott or C.L.R. James, he was no Samuel Pepys or John Evelyn either. His journal chiefly marked the turning of the farming year, recording the weather, crop rotations and household and business expenditure, as well as quotidian encounters with friends and neighbours. While the diary provides no window into Marchant’s inner world, eschewing the enrapturing highs and despairing lows of the period’s Puritan spiritual autobiographies, it clearly shows its author living a full and busy life. Besides owning one of the largest farms in the parish, he was a churchwarden, patron of the local school, dung and muck collector, land steward for Charles Seymour, 6th Duke of Somerset and resident freshwater fish expert.

One Fine Day is not a new edition of the diary but, rather, a smart and feeling rereading of it, complete with some fine black-and-white illustrations by Julian Dicken. Ian Marchant seeks to rescue his ancestor from the condescension of historians who would situate him as a déclassé yokel, and presents him instead as a forward-thinking, community-minded Tory who was on intimate terms with eminent Jacobites, such as Henry Campion. He was also frequently on a frostier footing with his sometime boss the Duke of Somerset, a capricious and proud member of the Whig Kit-Kat club, a man whom Ian describes, out of freshly discovered, intensely felt familial loyalty, as an ‘artisanal, lovingly hand-crafted, organically grown shit’. Lest that lead you to think of the book as a celebration of conservatism in all its manifestations, be assured that the author’s thoughts on the current version of the parliamentary Conservative party are even more withering.

Those ruminations emerge because of the way in which he splices together excerpts from the 18th-century diary with his own reflections on living with cancer during the first Covid lockdown. Ministerial corruption and misbehaviour during that period are only part of what catches his eye. As cars disappear and the roads fall silent, and the march of his illness makes him alive to the evanescent beauties of his surroundings, he discovers something of what the world must have sounded like to his ancestor 300 years ago: streets thrilling with birdsong, otters screaming in the river, the tolling of the curfew bell at 7.30 p.m. Shielding because of his treatment, and thus unable to socialise, he prizes hooking up in his imagination with this long-dead relative. They talk families, and pants (Thomas’s were made from the flax he grew), and whether XL jogging bottoms, which Ian is forced to wear, are anything like breeches because they pinch at both leg and waist. Sometimes they just smoke a pipe, have a drink in the dark, and enjoy the quiet together.

For all the book’s pathos, it skilfully avoids the whining and yawning traps of the misery memoir. This is partly a result of the double-temporality of the narrative: thoughts about cancer treatment trigger deliberations on bleeding, cupping and associated 18th-century medical practices; observations about Thomas’s fascination with touring mountebanks emerge in dialogue with a first-person account of cancer care under the NHS. But it is also a matter of Ian’s unsparing sense of humour in even the grimmest of circumstances. Thus, not long after his diagnosis, he mimics his ancestor’s laconic style of diary entry – ‘Weather hot; planted turnips; bought a heifer for 5s’ – with one of his own: ‘Wet horrid day. Went shopping in Leominster and pissed the car seat. Got the shits. Everton 1, Brighton 0.’  One Fine Day is one very fine book.