More on Vain as a Peacock from Infoplease:

• Vain as a Peacock - Vain as a Peacock (See Similes.) Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894 ...
• Dictionary of Phrase and Fable: V - Definitions, origins, and illustrative excerpts for words, phases, and literary allusions starting with "V"
• Similes - Similes in common use: BALD as a coot. BITTER as gall,soot. BLACK as ink, as a coal, as a crow ...