Trading in churches and taking the spare revenue was all very well, but how to get hold of the cash when you are working and living abroad? Mediaeval Europe actually had quite a sophisticated banking system and here a banker organises something that is between a bill of exchange and a cheque for Simon Langham. This means that money collected by his proctors in England can be deposited with an Italian banker in London. A note is then passed to the cardinal, this allowing him the right to draw the same sum, on presentation of the note, from the offices of the bank in Avignon.
The banker is then left with the task of making sure the right sums of hard cash are moved around Europe so they are where they are best needed. An example below in favour of Simon Langham survives in the Westminster Abbey muniments collection:
Michael of Strozze of the old company of the Strozze of Florence. The said four parcels of twenty thousand florins of the chamber of the said company of Strozze for Monsieur the Cardinal of Canterbury, this letter for our companions in Avignon where they can be had by the said Cardinal.
Given in London the 13th of December in the year of grace 1372.