I located the following article of interest on the BBC News website:

http://news.bbc.co.uk/1/hi/england/devon/7248786.stm

An entry in The House of Commons Journal for 1647 reports that Squire Richard Cabell III of Buckfastleigh in Devon was fined by Parliament for siding with the Royalists in the English Civil War.  Later, he retracted his support for King Charles I and was pardoned.  Undoubtedly, this act angered local people who depended upon The Duchy of Cornwall for their livelihood.  Perhaps for this reason, malicious stories about this unprincipled squire abounded.

In one such story, Squire Richard Cabell III reputedly accused his wife of adultery and a struggle ensued. She fled to nearby Dartmoor but he recaptured and murdered her with his hunting knife.  The victim's pet hound exacted revenge by ripping out Cabell's throat and some say that its anguished howls can still be heard at night upon the moor.  In reality, Cabell's wife actually outlived him by some fourteen years but the legend nevertheless persisted.

There are parallels between this story and the legend of the wicked Hugo Baskerville that was reported to Sherlock Holmes by Mortimer in The Hound of the Baskervilles.   Later, Holmes solved the case when he noticed a resemblance between a 1647 portrait of Hugo dressed as a Royalist and another character called Stapleton.  It is probable that this element of the Baskerville legend was suggested to Arthur Conan Doyle by Bertram Fletcher Robinson.   Fletcher Robinson acted as the 'assistant plot producer' and was a history graduate.

Around late January 1907, one Cecil P. Turner wrote to ACD and apparentlly enquired whether The Hound of the Baskervilles was founded upon the legend of the Black Dog of Hergest Croft at Kington in Herefordshire.  In his reply to that letter, ACD wrote that the story  "...was really based on nothing save a remark of my friend Fletcher Robinson's that there was a legend about a dog on the Moor [Dartmoor] connected with some old family".

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