The Encyclopaedia series was a winning format when it first appeared and one that has stood the test of time well, setting the standard for design-led instruction books where each spread is an entity in its own right. Several of the volumes have been revamped and, although I can’t see any evidence that this one is more than a straight reissue, it retains a fresh and inviting feel.
There are two distinct sections, Techniques and Themes and the combination of what to do and what to do with it is pretty much unique, most calligraphy books going for just one or the other.
Techniques covers all the things you’d expect, from basic penmanship to letterforms in Carolingian, Copperplate, Italic, etc. Diana also includes extras such as gilding, the use of quill pens and ornamentation.
In Themes, she gives extensive examples of the sort of work you can produce, with illustrations from a variety of contemporary practitioners. There is a limited amount of detail here, so this is more a gallery than a series of projects, but the extended captions and chapter introductions go a long way towards giving you ideas to work on.
If you want what is effectively two books in one, you’ll get excellent value for money.