Exaviator,
You bring back fond memories of the TAA and Ansett days of the Sixties (and beyond to their demise). Therein also lies a possible "origin" of the fifth bar.
Actually it was not a bar, but a symbol. Management Captains, in addition to the regulatory 4 bars had an additional symbol, in TAA's case it was a 6 pointed star, much like the Star of David. (I don't know of any connection between El Al and TAA).
Whilst we're strolling down the TAA memories lane, let's not forget two and a half bars, First Officers in command of a single pilot aircraft less than 5700 Kg / 12,500 Lb, Twin Otter, Dove etc......
Regards,
Old Smokey