Stitch Up.

As I’m sure I’ve mentioned, my wife and I have watched a lot of British police procedurals, so we’re familiar with the slang phrase stitch up, defined by Green (sense 3) as “(UK Und./police) of the police, to incriminate a person in order to ensure a conviction by planting evidence, faking confessions etc.; also in non-police use” (first citation 1970 [UK] G.F. Newman Sir, You Bastard 127: Your confederate has just about stitched you up). My wife asked me what the underlying metaphor was: stitching someone into a bag? Green doesn’t say explicitly (though under the general heading stitch up v. he has the bracketed [sewing up a garment neatly and conclusively]), but I found a discussion at the Stack Exchange English Language & Usage site; the question is specifically about “stitched up like a kipper,” so the answer that seems most useful starts with the kipper: I’m not convinced it’s a “mixture of similes”. I can’t find any relevant references to like a kipper prior to about 1970, and I…