Ms. Gary has done her research into the charms, simples and cures of Cornish wise women but as a whole the cultus of the Bucca is a modern semblance as there is no historical evidence of the cult outside of Penzance and Mousehole, which she is seemingly mum on. Yes, the works of both Robert Hunt and William Bottrell hint at the possibility of the Bucca as being the 'Old Cornish god of storms' but this is fundamentally based on the writings of Rev W. S. Lach-Szyrma, not empirical evidence.
However, the methods she presents are tried and true. I disagree with her presentation that the cunning folk by large used grimoires as most held laborer jobs and therefore the likelihood of them being able to read Latin, Arabic or even vernacular English is for lack of a better word unlikely. Yes, I am aware that many learned from others who may have been able to read such languages or possessed such books as a talisman but this is a completely moot point as again there is little statistical evidence to prove yea or nay.
Without sounding too critical much of what she presents can be found in the writing of Kevin I. Jones, Nigel Jackson, Nigel Pennick and Doreen Valentine. I found her section on 'Rites of the Moon' to be very brief and by large unhelpful. I supplemented it with rituals from Raven Grimassi's book 'Old World Witchcraft' and Raymond Buckland's 'Complete Book of Witchcraft'. Also, I didn't care for the initiation section as it seems somewhat antithetical IMO. Instead read Andrew Chumbley's 'The Leaper Between'.
As I said before much of her work can be found elsewhere. Owen Davies addresses the cunning path in his book 'Poplar Magic', W. Y. Evans-Wentz addresses the fairy faith/places of power/the bucca in his book 'The Fairy-Faith in Celtic Countries', Nigel Jackson addresses the tools of the cunning/the witches' compass in his book 'Call of the Horned Piper' and Kevin I. Jones addresses the trade of the witch in his book 'An Joan the Crone: The History and Practice of the Cornish Witch'.
Lastly, the 'Furry Nights' are fragmentary spinets of folkloric rituals that were common in Cornwall's historical antiquity but not so much now. While her integration of them into the modern Cornish witch-cult is interesting they leave me with more questions than answers. Also, and this is just a personal gripe of mine, she doesn't source her rituals. For example, in her Troyl Hood rite there is a line that reads 'here's to the devil with his wood pick and shovel, digging tin up by the bushel with his tail cocked up,' which comes directly from the story 'Duffy and the Devil'.
Yes, I find deep afflatus from her writings but when I'm forced to pay £15-20 (about $35 - 40) from Troy Books it acerbates me. She also has written 'The Black Toad', 'The Charmer's Psalter' and 'Wisht Waters'. I have all of them and I can honestly say that 'The Black Toad' seems much more historically in tune with what the cunning folk actually did. The Charmer's Psalter is a over priced book of psalms and as for 'Wisht Waters' it's an overpriced book on water magic.
Despite working with the bucca I don't recommend this author despite how she has influenced me for personal reasons. I think authors such as Cassandra Latham-Jones and Cheryl Straffon avoid the witch wars and place importance on scholarship over tradition.