I've come across this phrase - "a diabolical liberty" - a few times recently, most notably in a Jeffrey Archer book. I've never heard it before. A Google search comes up with some bands, comics, and movies, all from the UK, which, combined with Archer's use, leads me to believe it's from across the pond.

Am I to assume it's approximately equivalent to "giving someone enough rope to hang himself" or a "double-edged sword"?

Is there any known etymology?