We've been stuck on P for a couple hours, so I'll bump us along with a Papua airmail. The one-shilling George VI issue:

And since we might as well take a break from Queensland, I'll take the liberty of adding Q, too, setting the table for an R.
We've strayed off into state stamps, so perhaps a provincial revenue?

There, a bit of a palate cleanser...sort of like a philatelic sorbet.