The book tells the story of Jersey-born William Mesny, who ran away to sea as a child, reached China in 1860 aged 18, and became variously a smuggler, prisoner, horse trader, hotelier, blacksmith, photographer and gun runner, as well as rejecting numerous other job offers. He joined the imperial army to fight the Miao rebellion in Guizhou province, eventually rising to general and taking advantage of his rank to travel around the country, visiting every single province.

A writer, botanist and adviser on military, economic and infrastructural development to various high-ranking late Qing statesmen, including Zhang Zhidong and Li Hongzhang, Mesny eventually settled in Shanghai and wrote about his travels, experiences and opinions in the self-published Mesny’s Miscellany. Implicated in a dodgy arms deal, he eventually fell from grace and never recovered, dying in relative poverty in 1919.

The book’s author, Sinophile British travel writer David Leffman, became interested in Mesny when he heard, on a trip to Guizhou, about his role in the Miao rebellion. Biography rather than history, the book is nonetheless scholarly in its approach, and has clearly been distilled from an immense amount of research, including Leffman’s retracing of Mesny’s footsteps around China over a 15-year period.

This is good, as Mesny himself is clearly an unreliable narrator, constantly bigging up his own importance in his writings; he particularly liked to take credit for any innovation introduced by a Chinese official he knew.

Mesny is a fascinating character: unpredictable, contrary, often tactless, but also charming, garrulous and genuinely passionate about creating a stronger China. Largely free of the usual colonial-era jingoism, he was fascinated by and appreciative of China – and Chinese women, of whom he married two. Strongly Christian but approving of Buddhism, he was focused on British trade interests but also strongly anti-opium, having seen what it did to his local staff. A restless character as much as an entrepreneurial one, he initially drifted into fighting for the imperial army out of a combination of financial opportunism and boredom.

Despite his sympathy for China, though, he remained impervious to some aspects of the country’s culture, particularly the need while travelling to give face to local officials, which got him into all sorts of scrapes. In 1883, for instance, he spent three months in a boat moored outside the gates of Guigang, Guangxi, refusing to move on until he received an apology for a breach of protocol.

Perhaps his greatest hobby horse was the opening up of China to trade, particularly the interior, and the infrastructure – principally, railways – needed to make it happen. He was constantly advancing ideas for technological modernisation, most of which were stonewalled by self-interested local authorities or simply ignored.

Leffman’s telling of this tale is well-paced, his writing elegant and his knowledge of China impressive. The book is full of period detail, much of it showing just how remote inland China still was: in the 1860s the 800km journey up the Yangtze from the Three Gorges to Chongqing took six weeks, longer than a sea trip from Shanghai to London; while a Chinese general Mesny meets when he gets to Chongqing is amazed to discover that foreigners have knee joints.

The travel yarns are endlessly entertaining, although sometimes you question what the point of Mesny’s journeys was: an epic two-year trip to Hami, Xinjiang, to try to convince local authorities to accept a European loan to fight Russian territorial incursions was rendered irrelevant by the signing in 1881 of the Treaty of St Petersburg six weeks before he arrived, for example, while Mesny becomes an expert on Tungking without getting closer to the northern Vietnamese kingdom than Yunnan.

As Leffman often points out, Mesny wasn’t as important as he liked to paint himself. As one of the new Westerners travelling around inland China during a turbulent period of growing foreign influence, however, he was at the centre of a rapidly changing China, and his story provides a unique insight into a country at the end of an era, about to march headlong into modernity.