And the first prize is issued to Noggin.
I have to admit that I made a total b***s of the question - but it was a teaser as I knew the answer to be exactly as Noggin says (at least I knew it after the conversation in question..I genuinely did think it was a "regional QNH").
Now that we have the dictionary definition of the "regional pressure setting", I'd be curious to hear of any written references to "regional QNH" (like in the CAA PPL Navigation written examination papers).