D.J. Taylor, a British writer of formidable accomplishments — several well-received novels, as well as biographies of William Makepeace Thackeray and George Orwell — but little known in this country, has pulled off an impressive and wholly engaging feat in “Derby Day.” Set in London and environs during a few weeks in the reign of Queen Victoria, it is not merely a work of historical fiction but one written in a language appropriate to its time — i.e., it is a Victorian novel, the prose of which brings to mind Thackeray (of course) and Dickens, yet never smacks of cuteness or contrivance. It is delicious fun and can be read purely as such, yet it is also a serious novel about a society caught between the familiar and the new, in which “the world is changing” and leaving many people behind.

The Derby to which its title refers is the great horse race that has been run at Epsom Downs for centuries, an event that brings together the whole range of British society from the highest to the lowest, from “swells in frock-coats” to “tiny, starved boys” to “butchers’ wives from Shoreditch” to “apprentices in cheap imitations of the fashion” to “persons in the last extremity of poverty huddled up in ditches, recumbent by the rail, or frankly begging along the course.” The dramatic race itself, with its entirely satisfying outcome, occupies only a couple of paragraphs, but Taylor lavishes page after page on the human spectacle:

“In Epsom everything is in turmoil, with ten thousand visitors crowded into a town that usually holds eight hundred. The inns are crammed to the rafters and there are people sleeping in the fields beyond Cheam and Ewell village. In London and its surround a hundred thousand go to sleep with the thought that at four, five or six o’clock they must rise up and make haste for the railway station, or the cab station, or the road. Beyond this — beyond the Home Counties, beyond England even — there are sportsmen making uneasy calculations about the procurement of evening newspapers and their proximity to telegraph offices. The court knows about it. Half of parliament at least will be attending it. The bench of bishops will not go unrepresented, and the diplomatic embassies cannot be kept away. . . . A radical politician has condemned it, and a Methodist divine preached against it, but one might think that something which unites a widow in Kensington Square, an apothecary in St. John’s Street and the wife of a Hoxton chandler is more democratic than the reverse. Chelsea is going, in carriages and coaches-and-four. Clapham is going in tax-carts and bang-up ponies. Kensington and Brixton are going by way of the Southern Railway or a succession of omnibuses, and Whitechapel and Poplar will be arriving on foot, for what is a sixteen-mile journey under the June sunshine when there is Saturnalia in view?”

Much of the excitement swirls around a horse named Tiberius, a beautiful creature but one about whom “there was some mystery.” As the novel opens, he is owned by Mr. Davenant, “a man of about forty, who had lived in Lincolnshire all his life,” a “widower, which people said had made him melancholy, and he had a backward daughter, a girl of about fourteen with white hair and a big moon face, which people said had made him more melancholy still.” He farms the same hundred acres his father and grandfather farmed before him, but he does so with little enthusiasm and to no apparent gain. His world is slowly falling to pieces, which makes him an inviting mark for George Happerton, an utterly unprincipled London swell who has his eyes on Tiberius.