The truth, the whole truth, and nothing but the truth : the English Corn Returns as a data source in economic history, 1770-1914.

From 1770 to 1914, the British Government collected weekly price and quantity data for all types of grain traded in many market towns; these ‘Corn Returns’ were published in the London Gazette. We computerised the data published 1770-1864, totalling around 6 million data points. Here we describe the nature of these data; discuss why, when and how they were collected; consider their accuracy and biases; describe how we computerised them; and offer caveats in using these – and similar – data. We highlight the problem of drawing valid inferences in the face of price impact from fluctuating grain quality and rising imports