In March 1950, an RAF wing commander and trained accountant called Charles Reep turned his eye for numbers to football. Reep, who had become interested in the sport in the 1930s and was fascinated by Herbert Chapman's pioneering Arsenal team, had returned from the Second World War to find that the tactical revolution he'd witnessed before had stalled. Finally, at half-time during a drab Division Three game between Swindon Town and Bristol City during which he watched countless attacks amount to nothing, Reep's patience ran out. He grabbed a notebook and a pencil and began furiously jotting down what happened on the pitch – he started counting the number of passes and shots, in one of the first systematic attempts to use data to analyse football. Seven decades later, the data revolution has reached the grassroots – fans are fluent in xG and net spend, and the top teams pluck statistics PhD students straight from university in the search for an edge.