This discovery is very interesting, but it is extremely unlikely that Drake was just giving away such high denominations of coins!! Here is an article that attempts to be more reasonable in explaining this discovery:
http://fullcomment.nationalpost.com/201 ... cis-drake/
"Bawlf argues that Bruce Campbell’s recent metal-detecting find suggests that Drake may have given coins away to the people living along the coast. But that defies logic. In Tudor times, people did not have change to throw around. A shilling was more than a day’s pay for a soldier, and worth about twice the daily wage of one of Drake’s sailors. The fact that the coin was found near a 1900 Canadian penny, an 1891 five-cent piece and a 1960s dime suggests less sensational origins.
But Canada’s media liked the Drake shilling theory quite a lot. Journalism requires a bar of proof that’s lower than the one used by academic specialists. In recent days, a single coin became the story of a man who had found a piece of authentic history, possible/likely proof that, in Tudor times, Drake or someone traveling with him either tossed money to the locals on Victoria’s mud flats or walked the Vancouver Island shore with a hole in his purse.
That kind of logical leaping happens a lot. Manuscripts and collections of papers that come up for auction must, according to news writers eager to sell their scoop, be pivotal to our understanding of Canada. Maps and artifacts in foreign collections are vital to our nationhood and must be returned....."
"No historian would take a flier on an old coin and connect it to history in a concrete way unless it was found in some place that was undisturbed, like, say, A grave in the Arctic permafrost or undisturbed soil at an archaeological site. But journalists want to believe. A guy finding an oddball coin worth a few hundred dollars isn’t just a decent page-3 local story, but “proof” that Francis Drake enjoyed the delights of southern Vancouver Island in the 16th century. Alert the front-page editor!"
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I concur with Minimalist that a more mundane explanation is likely.