I hope it is not considered poor etiquette to follow up on my own message - if so, please excuse this.

Just seen on perldoc's diagnostics (emphases are in the original):

(Note that this does enable perl's -w flag.)

So the throwaway comment on scoping turns out to be relevant after all. Once more the Universe says 'RTFM'.

I suspect that is probably about it...? Nothing further, your honour.