Unlocking Upcycled Medieval Data: North Sea Networks, People, and Commodities in the London Customs Accounts 1380-1560

'Unlocking Upcycled Medieval Data' is a collaboration of British and German digital historians to realise the potential of a unique collection of medieval sources that tell the story of Anglo-German trade. Our project will advance knowledge of pre-modern trading networks and economies through the first comprehensive analysis of the detailed 'particular' London Customs Accounts (LCA) - probably the single largest surviving serial collection of medieval trade documents in Europe. The LCA are a crucial record of London in Europe and a vital element in the story of the German cities' relationships with the world. The value of the LCA is in their potential to reveal the practice and impact of late medieval trade through people, relationships, and material objects. For example, John Yeoman's ship 'Trinity Bulle' arrived in London on 13th November 1480 carrying goods of 22 different merchants, both Hanseatic and Flemish. One of them, Frank Matthew, imported goods ranging from a barrel of printed books to '14 dozen Jesuses' and a box of toys. This illustrates transnational networks, the growth of print, religion, and the material culture of everyday life - and it is just one consignment from one of 20,000 ship movements recorded in the LCA. The LCA have recently been transcribed and published as 40 PDFs containing more than 10,000 pages. Yet it remains extremely challenging to harness them to answer wide-ranging or longitudinal questions. Their scale frustrates manual analysis, while their format and complexity presents a barrier to conventional digital tools. We will unlock the LCA for comprehensive analysis through our methodology of data upcycling. Our approach will open the LCA for AI-assisted analysis, bridging the gulf between traditional historical source editing and digital humanities approaches. To do this, we will develop reusable methods to upcycle existing transcripts of semi-structured historical sources into open and reusable machine-readable data, while respecting medieval historians' relationships with their sources. We will also develop data enrichment workflows to cut through the complexity of medieval data to trace material objects through time and space. We will apply the upcycled data to some of the most enduring questions in late medieval social and economic history, including how the standard narrative of fifteenth-century turmoil and economic crisis can be reconciled with the flourishing cultural life seen in micro-historical studies? We move beyond money to look at networks of people and things transnationally to revise understanding of the consumer economy in North West Europe in the fifteenth and sixteenth centuries. Contributing to these important historical debates, and providing access to the sources, will be of great significance not only to historians, but to economists, archaeologists, and the cultural heritage sector. Delivering the first comprehensive analysis of the detailed LCA will open new perspectives on the prosperity of late medieval Europe, with implications for interpretations of long term growth and development. Meanwhile, our insights into late medieval material culture will shed light on the often ephemeral objects of everyday life that are underrepresented in other sources and museum collections. We will amplify our work through our partnership with the Europäisches Hansemuseum to tell transnational stories to wider communities through data and collections. Our methodological innovations will also be of great help for digital humanists working with other semi-structured data.