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If you are aware of the bird you wish to learn everything about, this book is great. However, if you want to identify a specific bird, or distinguish between two birds, as I often do - this is not the book for you.
This may be published by the RSPB but for a novice it is very confusing. It classes birds by type (OK) but if you don't know what bird you want to look up it is hopeless. It does not classify alphabetically. Could be a lot better for a beginner who is learning the difference between dunnocks and finches???