Barkle in the 1500s was a mid-Cornwall surname. Look out for a coming map of the associated name Bartle in this same period. Or does the spelling Barkla suggest an origin in Barclay? Barnicoat was more widely spread, its geography perhaps suggesting a sea-borne route from its Devonian origins. Barrett was common across mid and east Cornwall in those days but rarer in the Cornish-speaking west.
And some news on the surname front. Work proceeds in fits and starts on a list of the most frequent surnames in each Cornish parish in 1641/42, based on the Protestation returns. This will be in the same format as the ever-popular page 18th century surnames by parish and will be coming soon.