Back in the mid-2000s, I read two books of Garry Kilworth's Welkin Weasels series, a set of two trilogies about anthropomorphised mustelids, one trilogy set in a version of medieval England and the other set in a version of Victorian England (plus other parts of the world which the characters travel to).
A tagline printed on the back of each of these books, at least in the editions that I read from the library, was:
As good as Brian Jacques, or your money back!
This is of course a reference to Brian Jacques's celebrated Redwall series which also features anthropomorphised animals, although the stoats and weasels in his books are generally the bad guys whereas in Kilworth's books they're the main characters, both good and bad.
But what is the story behind this tagline? Were Kilworth and Jacques old friends and this was a joke between them? Did Kilworth see himself as a competitor to Jacques? Did any serious complaints ever happen along the lines of "not as good as Brian Jacques, I want my money back"?
Strangely, Google lists no results when I search the exact phrase "as good as Brian Jacques or your money back". But I definitely remember it on the covers of those books.