Though not a contender for “greatest counterfeiter”, there is also William Chaloner (1650–1699), who had a similar idea (“the safest place from which to pass his money was the Mint itself”), and did battle with Sir Isaac Newton. There's a great book about this called Newton and the Counterfeiter: The Unknown Detective Career of the World’s Greatest Scientist by Thomas Levenson; I wrote a blog post about it some years ago, with the subtitle “What happens when Newton’s laws are violated”: https://shreevatsa.wordpress.com/2010/06/04/dont-mess-with-a... (aside: the free wordpress.com hosting injects lots of ads these days sadly)

Tired of this humiliation, the British tried him for counterfeiting. He countered that only legal tender could be counterfeited, and sovereigns were no longer legal tender. He won the case.

"Money of their Own" by Murray Teigh Bloom

Shameless plug: if you like my writing, I mostly write about AI these days: https://www.ignorance.ai/

When they caught the counterfeiter, he was let off on a technicality (his coins were not an exact copy - they were missing a dot, and they were not magnetic while the real coin was), but the coins were so common they were accepted as legal tender.

(At the time people said that the counterfeiter was fined so much he had to keep the presses running all night.)

"These four made it rain so hard it created a noticeable boom in the Portuguese economy."

Which highlights to issue with counterfeit money - its pretty easy to create, but then the hard part is laundering it.

The whole story is just staggering to think they got away with it for so long.

No it wouldn't. Probably an off by factor of 1000 error.