There's been a bit of a publishing run on the gazetteer format recently. Partly it's to do with our current craze for all things mid-20th century (think of those recently re-issued Shell County Guides), and partly because it's such a useful format, allowing an author to be simultaneously comprehensive yet specific, general and minute. The gazetteer way of doing things lets you impose order on an inchoate mass of information without any risk of pummelling out the quirky and particular. Above all, it leaves space for things that won't quite fit.

All these strengths Christopher Lloyd manages to utilise in his hugely enjoyable In Search of a Masterpiece, without any suggestion that he's chasing a glib retro-chic vibe (this book is too big, anyway, to fit in the imaginary glove compartment of an imaginary Morris Minor). Nor is there any whiff of parochialism. Lloyd's searching ground for his masterpieces is not British and Irish art, rather it is art that hangs in British and Irish galleries, all of them public, most of them free. The result is a cosmopolitan spread of work whose origins range from Italy in the Quattrocento to wartime New York. What's more, Lloyd is just as interested in work that hangs in small or overlooked galleries as in what's on show at Tate Britain or the National Gallery of Scotland. He takes us to Bushey, Orkney and Maidstone, ferreting out unlikely masterpieces along the way: who knew that Leicester's New Walk Museum held the biggest collection of German expressionist paintings in the country?

Lloyd  who was surveyor of the Queen's pictures for nearly 20 years  is exactly the companion you would wish to take with you on a museum crawl: knowledgeable, urbane and discreetly impatient with dense art-historical lingo. (Anyone who describes a sun-drenched Mediterranean port scene by Claude Lorraine as the equivalent of a Campari before an early lunch is clearly not going to drone on about semiotics). Above all, he seems to understand exactly what it feels like to stand in front of a painting that makes you prickle with pleasure for reasons you don't quite understand.

Take the thumping wonder of Uccello's The Hunt in the Forest, c1465, which hangs in the Ashmolean. Its funny little pin men astride fairground horses don't exactly invite empathy. The dogs seem like heraldic motifs rather than slobbering hounds keen for the kill. But still the painting draws your eye deep into the dark forest and holds it there for longer than makes sense. Lloyd knows exactly what's going on, and points to the way that four trees in the foreground divide up the picture space in equal parts, forming right angles to the logs in the undergrowth, so that your eye is led to a central vanishing point. He is spot on, too, with the suggestion that "the poetry of the picture comes from the impenetrable silence of the forest and the passing clatter of the hunt", in a single sentence managing to add sound and movement to an image as flat as a decorative frieze.

Although Lloyd is careful to cover all periods of art  he goes right up to 2005 with Bridget Riley's Red Movement (Southampton City Art Gallery)  you get the feeling that he finds it easiest to love early Italian painting. At Christ Church, Oxford, where he started his curatorial career, he draws our attention to a stunning Virgin and Child and Three Angels ascribed to Piero Della Francesca. Its severe grace sets it apart from the fleshy gurning of Renaissance madonnas and their plump-cheeked tots. Piero's virgin is austere and two of his angels are far too dignified to bother with wings. Looking at the painting's quiet self-containment makes you realise what Rossetti, Hunt and the rest of the Brotherhood were after when they embarked in 1848 on their homage to the "pre-Raphaelites".

Travelling to GF Watts's gallery at Compton, Surrey Lloyd picks out Found Drowned, a melodramatic pot-boiler which has often been categorised as mere social reportage, illustration at best. It shows a young woman pulled dead from the Thames, the locket clasped in her hand a clear indication that she has been trifled with by some heartless cad. The narrative is clunky, the symbolism ploddy. But Lloyd pushes us to see beyond Watts's windy Victorianism, pointing out the artist's ability to produce "magical effects". Surely, he asks, Watts is an artist who deserves a second, and sustained, look.

In the same way Lloyd isn't afraid to stick up for Gauguin, a painter whose descriptions of a south sea island paradise often make him hard to like. Never more so than in Nevermore, the painting of 1897 (Courtauld Gallery) that depicts Gauguin's Tahitian wife Pauhura stretched out in a pose suggestive of what the painter himself called "a certain long-lost barbarian luxury". Much about it  especially the over-determination of the figure's racial and cultural otherness  makes one prickle, this time with involuntary embarrassment. But Lloyd acknowledges the discomfort while still insisting on the painting's status, drawing our attention to its beautifully finished surface and stunning use of colour, not forgetting its obvious impact on the next generation of Picasso and Matisse.

In the first sentence of his preface Lloyd emphasises that what we have in our hands is "a personal selection of paintings", a kind of visual equivalent of Desert Island Discs, rather than any sustained attempt to define "a masterpiece". And some of his choices are idiosyncratic, not to say downright wilful. For instance, Constable is included, but he is represented by a view of Salisbury Cathedral rather than the more obvious East Anglian mill ponds. Stanley Spencer is here, but his only landscape is of Southwold, more than 100 miles from Cookham. The great Victorian panoramist Frith, meanwhile, is represented not by one of his jostling crowds but by an intimate picture of his daughters practising their archery.

Perhaps, though, this doesn't really matter. The book is designed not as an advertisement for individual paintings, but as a reminder that good, even great, work may be found in the most unlikely corners of Britain and Ireland. As a result, the next time you find yourself in Bushey or Maidstone with half an hour to kill you might just eschew the usual visit to an identikit coffee bar and find yourself instead gusted along by Christopher Lloyd's contagious pleasure to seek out a local piece of world-class art.

The Short Life and Long Times of Mrs Beeton by Kathryn Hughes is published by Harper Perennial.