Though written as an academic publication, this book moves quickly to document changes in agricultural practice caused by fluctuations in population and food demands. Thirsk's basic premise is that at several points in British history (incuding after the black death, and during the agricultural depression of the late 19th century) overproduction of commodity crops (such as corn and grain) has been followed by an "alternative agriculture" that involves diversification of crops to include industrial crops and expanded production of fruits and vegetables. When farms switched from grain to vegetables they got smaller, more productive, and more labor-intensive, and introduced new and healthful foods to local populations. New foods were often adopted by the elite before becoming available to the lower and middle classes.
Reading this book in 2008, eight years after it was originally published, it is all the more relevant. The state of agriculture is changing quickly: a glut of low-priced commodity crops could have inspired more diverse farming, but a movement to production of fuel crops then increased commodity crop prices. At the same time, however; the locavore movement is demanding a transition to the type of alternative agriculture that Thirsk documents. Although Thirsk focuses her research solely on British agricultural history, her book provides terrific perspective on all of these issues.