The Portable Antiquities Scheme (PAS) was started in response to the Treasure Act of 1996, which legally obliged those finding gold or silver items at least 300 years old or prehistoric objects of base metal to notify their local Finds Liaison Officer or the British Museum by sending photos of the object, where it was found, and on whose property. A committee then uses a formula to determine the share of the market value that goes to the finder and property owner. Non-metal finds or non-prehistoric base metal are photographed and fully recorded in the PAS database, which can be searched in multiple ways and consulted by archaeologists, scholars, and the general public.
Users need to register (for free) to make full use of the search capabilities of the database, which has over 1.5 million entries. A search on medieval finds in London turns up almost 800 items, including 102 vessels, 61 pilgrim badges, 52 coins, 44 buckles, 38 tiles, and 18 cloth seals, among other items. Among the useful resources on the PAS site is a Medieval Coin Guide where over 50,000 medieval coins found in Britain can be searched by period, type of coin, and mint with the use of an interactive map.
Early Medieval Corpus Single Finds of Coins in the British Isles, 410-1180: Searchable database maintained by the Fitzwilliam Museum, Cambridge includes single finds from the UK. Also searchable are coins published in the Sylloge of Coins of the British Isles (SCBI) series as well as a Checklist of Anglo-Saxon and Viking hoards from Britain and Ireland. The database allows users to search for coins from specific mints (such as London), periods, moneyers, and rulers, and to map the location of coin finds.