The Royal Mail’s Postcode Address File (PAF) is one of the most important yet often overlooked datasets in the UK. It underpins everything from mail delivery to e-commerce checkouts, credit checks, and emergency response systems. But PAF didn’t appear overnight. It evolved over decades alongside changes in addressing, technology, and society. This post explores the history and evolution of PAF, from the early days of postal districts to the digital infrastructure we rely on today. Before PAF: The Foundations of Modern Addressing (Pre-1970) 1850s–1910s: Postal districts and sorting efficiency Major cities such as London began using postal districts (e.g. “EC” or “SW”) in the mid-19th century. These were introduced to improve sorting efficiency as urban populations grew rapidly. However, outside [...]