SOME BOOKS CAN be fully appreciated only through a haze of love. Celebrity memoirs, for example. If you truly worship a particular star, you may forgive him his lame childhood reminiscences and clunking prose (or that of his ghostwriter). You will be glad, simply, to have had the illusion of spending some time in their company. As for the rest of us, we may sneer, but we are missing the point. These books are aimed only at the converted. Sceptics are not invited.

It's the same with these two new books about chocolate. To buy into them fully, you would have to be the kind of person who describes themselves as a chocoholic; who sighs that chocolate is better than sex; who sees confectionery as the root of all pleasure. More specifically, you would have to be mad about either Cadbury's or Green & Black's. Or else why bother?

I had a problem, therefore, with the Cadbury's book before I had read a word. The sensation that Cadbury's Dairy Milk induces in me is not love but nausea. I was not predisposed to enjoy the feeble pun of the title (Cadbury's Purple Reign - geddit?) or chapters with such headings as The Overseas Businesses Go from Strength to Strength. I was surprised, therefore, how much there is to appreciate for a Cadbury's sceptic.

The illustrations are stunning, stretching from 1831, when John Cadbury first switched from selling coffee to cocoa, to the present day of Freddo the frog and Galaxy Ripple. Those old glass-and-a-half adverts are just as nostalgic whether you love or hate the stuff. John Bradley's accompanying prose is a solid business history of the firm, peppered with interesting details. He does not whitewash the fact that in the early days of the 19th century, Cadbury's cocoa was adulterated, with potato flour, sago and treacle.

If the book has a fault, it is - surprisingly - a little passionless, perhaps reflecting Bradley's 24 years of experience working for Cadbury's. For him, chocolate is business not pleasure.

You could not level the same accusation at Sweet Dreams: The Story of Green and Black's, co-authored by the husband and wife who first marketed this organic chocolate. If Craig Sams and Josephine Fairley displayed any more passion for their subject, they would explode.

Initially, I felt more warmly towards this book, purely because I love Green & Black's. The chocolate-brown wrapping on the bars inspires a fetishistic devotion. The basic 70 per cent G&B dark bar may not be quite as yummy as Scharffen Berger chocolate (available only in the US) but it's still better than anything else on the UK market at the same price, and ethical to boot.

I floated into the book on a wave of chocolatey affection. Sams and Fairley are at their best when describing the basic decisions behind building the brand - how they wisely decided to stick with superior versions of “normal” flavours such as nut, cherry and mint instead of branching out into lavender or Earl Grey; how they found the right ice-cream maker to manufacture their “fudgy and moreish” chocolate ice-cream.

As recently as 1997, the business nearly failed, after some financial mismanagement. They recovered, though, and it was all plain sailing until they sold (out) to Cadbury in 2005. “Actually,” write Sams and Fairley, justifying the decision, “these guys are good eggs. (Creme Eggs, of course).”

This gives a flavour of the book's style. Sams and Fairley write as if what they have done, selling chocolate, is the most important venture the world has yet seen. Sams calls the flavour of his Maya Gold bar “Wagnerian...[creating] an experience that transcends memory”. At one point, they say: “Actually, we don't think of our approach as saving the planet any more, but as saving the human race.” Even those of us who admire the fair trade work they have done with cacao growers in Belize may find this hard to swallow. Also worrying is the luvvie-ish name-dropping - Sams and Fairley hobnob with Sting and Trudie, Paul and Linda at “organic soirées...generously hosted by HRH the Prince of Wales”.

My love for the brand was tested quite severely. But it was nothing a few squares of G&B sour cherry couldn't solve.

Sweet Dreams: The Story of Green and Black's by John Bradley
Random House Business, £14.99; 272pp
Buy the book

Cadbury's Purple Reign by Craig Sams and Josephine Fairley
Wiley, £24.99; 352pp
Buy the book

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