Hi Pauline,
It's a great book - I bought my copy from ebay, new, so it must be being sold somehow.
The book mentions an Evan Garrett on page 117, in the year 1595 "the general consensus was that the inhabitants were 'already sufficiently provided of herrings' presumably after a successful fishery in the previous year, and only two men, Evan Garrett and John Stevenson, were licensed to buy herring from the Scotsman. Garrett purchased a barqueload at Ramsey of which, under the watchful eye of the waterbailiff, he was to dispose 'for the use of the Country' ; Stevenson was told to go to Douglas where he might have 'so manie herrings as will satisfy his want."
His source is Lib Canc 1595, 24
Hope that helps - let me know if you fancy doing a research exchange for any Cornish relatives you have :)
Beccy