To answer Trumpys' question from this thread:

http://www.electrical-contractor.net/forums/ubbthreads.php?ubb=showflat&Number=170227#Post170227

I believe that there were varying distances between mounting points in the 1950s & 1960s until 84mm became standard so the manufacturer (HPM in Sydney, Australia) supplied the outlets & switchplates with different mounting holes so the installer could select the pair of holes needed to affix the plate to the mounting points.

I haven't tried to push the knock-outs from the plates as I have no intention in mounting these items. When I do mount these outlets, they'll go on display boards & be held with silicone as not to damage them.

The large square outlet at the top has four sets of mounting holes for either use in 1 gang (84mm apart) or 2 gang (46mm apart for the width of the plate & 84mm apart from top to bottom) though it was not common to find many items on the 115 x 115mm plates (4 1/2 inches approx)

Ahh,
That would explain a lot.
I've never seen the 38 series used here as far as I can recall but I have seen a few of the 550 series installed.
That socket outlet with the skewed outlet looks a little strange.
It's amazing how the shape of the switch rockers and the general look of the switch-plates have changed over the years.
I have a small collection of older PDL switches and socket outlets here and they look nothing like the modern stuff, but at least if you accidentally drop a switch on a concrete floor these days, it won't shatter on you.

Thanks for the reply Darren!.

Here's the American version, made by Hubbell. As far as I can find out, these were an earlier version of our modern 3 prong outlet for 120V 15A. The one here in this picture has 240V to feed an European vacuum tube AM and SW radio. And it's rated for 240V as well as 120V, and has an old UL seal of approval too. The radio doesn't mind it being 60Hz vs its home 50Hz. :-)

I wish they'd make those pushbutton type switches for decorative effect; up to current codes of course.

This place house of antique hardware has such switches, some are claimed to be UL Listed and CSA Certified. Not all of 'em, though!

And classic accents is another place. Again only some of the switches are claimed to be U.L. Listed.

And kilian hardware some are "Now UL approved.".

A google search will find more.

Question: How are you supposed to connect wire to the Australian outlets and switches shown above? Those connection cups with the set screws look rather big to just hold a single 14 or 12 AWG wire.

The wire is simply folded back on itself to double up the thickness. In many instances, particularly for power points more than one wire is connected to each terminal. In this case, the wires are simply twisted together before insertion.
These types of terminals are very accommodating for different wire sizes and number of wires connected.

Looks like this outlet would require an exceptionally narrow box, one about 3cm wide and about 3 inches tall. I don't think I've ever seen one that size.

This type of outlet is known as an "architrave" fitting. That is, it's intended for mounting in a door/window frame or skirting board without a box. Even the standard size fittings are often mounted without boxes. Generally, boxes are only used in with brick or concrete walls. Hollow walls like Gyprock or Masonite use either a thin steel bracket with tapped screw holes, nailed to a stud behind the wall, or for retrofits what's known as a "plaster bracket" which is a similar thing but hangs on to the edges of the rectangular hole with two clips. If it's a timber or plywood wall the fitting is usually just screwed in with no boxes or brackets. Retrofitting onto concrete or brick walls is a pain, so the easy thing to do there is use one of the many size mounting blocks.

That just seems so different to the way things are done in the USA. That there is no box to attach via a connector the house wire cable to (strain relief, so no strain on the actual wire connections on the back of the outlet). And that here, the box also helps contain any flying sparks from a failing connection, so the embers don't find flammable building materials to set fire to.