Help me find this quote

[nineveh_uk]

It is, as will become obvious, almost certainly from a British comic novel, but since I can't remember all of the actual quote, googling is not helpful. I think it is describing a woman - possibly blonde, ditsy, or simply a bit naive, and is something like '[she had the] look of a [rabbit?] that has gone on [a spree/the loose] and was astonished by the result'.

All suggestions welcome! It's lurking annoyingly in my mind, but not sufficient to be useful for me to find it.

ETA: Identified by antisoppist as from Gaudy Night.