The next book in this series is The Invisible Grail, by John Simmons. This brilliant little book is all about "verbal identity": finding a distinctive and authentic tone of voice for your brand. It really inspired me to explore the role writing, language and story-telling can play in branding. It also guided me in trying to find my own distinctive voice for the brandgym books and this blog.
The book has some great examples of brands that use distinctive language, including Lush, Guinness, innocent and Pret a Manger. Here are some examples:
"The most powerful brand stories will normally be those that have the ring of truth."
"Encourage people to bring more of their personalities to work - and to give expression to that in their writing."
"Given a set of 'commandments', employees might plat acts of resistance. Yet, given a deeper understanding of brand values through storytelling, there is a stronger possibility that an individual will draw links between the corporate and the personal."
If the whole area of "brand voice" interests you and you're hungry for more, then Rob at Brand Story has written a good post on it here.