The medieval customs accounts record all imports and exports on which customs duties were payable, ship by ship, merchant by merchant. The meticulous detail of these accounts puts flesh on the bare bones of England's trade statistics, providing information on shipping, merchants and merchandise. One can trace the careers of the individual wealthy merchants or groups of merchants - whether they are from London, Bristol, the Hanseatic League, or Venice. The volumes and
prices of products - such as English cloth, salt, or furs - can be calculated. And even the trading patterns of individual ship captains can be deduced.

So that the whole process can be understood, all the other accounting documents relating to the London accounts for 1445-46 are also published in the edition. Furthemore, the technical Introduction explains the customs system and the Exchequer's accounting procedures.