I have trying to read more on my British hammered coins. This is quite a task because many of them have mushy or missing letters that impossible to read. The two volume set of books by Jeffery North has extensive listing for the English mints and the many moneyers who worked in them. Given that many of these coins are scarce to rare, how did North or other researchers know about all of the moneyers and mints? Are there records that have survived from the middle ages that provide this information? I can't believe that it's based upon the surviving coins that have been seen. For example, I purchased this Edward the Confessor penny from Heritage several years ago. I their description, they attributed the piece to the York Mint and the moneyer as "Stircol." There is no moneyer by that name in North, and the reverse of the coin reads, "+ STIRCOL ON EOFER." How this signify that this is a York Mint piece? I gave the reverse photo a quarter turn from the Heritage photo because I believe that the "+" (cross) should be at the top.
For the most part, answers to your questions can be found in North's 'Mint Towns' section and Bibliography. The coins are the primary source, of course. Those North did not see in hand he surely saw in print. Towns (more so than moneyers) are also known from a variety of historical sources. The Roman name for York was Eboracum. Under the Saxons, it morphed into "Eforwic" (Vol. 1, p. 246), abbreviated "Eofor" on your coin. North mentions a "Stircol" coining at York for Edward the Confessor on p. 186. A coin at CNG equates the signature STIRCOL with the Old Norse name "Styrkollr". It's all much more complex than plugging modern pennies into a coin board... but that's the fun of it! Wonderful coin, btw. https://cngcoins.com/Lot.aspx?LOT_ID=63091
North builds on decades of research. For example, the Numismatic Chronicle was first published in 1836, and the Journal of the British Numismatic Society in 1903. Hoards and collections have been published since at least the early 19th century which provide detailed listings of mints and moneyers. For Edward Confessor in particular this includes the collection of Anglo-Saxon Coins in the Swedish Royal Coin Cabinet, the second edition of which was published in 1881 and the specialist 2 volume (nearly 600 page) publication by Freeman "The Moneyer and the Mint in the reign of Edward the Confessor" from 1985