However, of course, Oz cars don’t follow these rules.  All Oz cars have the original Mk I (ie UK) style opening rear windows with the full length (height??) piano hinges...

Pretty sure your final comment is tongue in cheek.... noting that Mokes don’t have rear windows.. they have curtains..

Cheers, Ian

The standard Mk I has a front hinge about 7.5" long and the window surround looks like one piece from the outside of the car. The Mk II doesn't have the long hinge showing, but has two parts showing as the surround. You can see places where the parts come together near the middle at the top and middle at the bottom.

EG, your Wolseley 1000, most likely has the Mk II surrounds and Mk II windows.

What is the difference between Mk1 and Mk2 rear windows.
Curious as to which EG and my Australian car have.

I know my Moke is Mk2, but the side windows seem to be missing so I can't do a comparison...

Quite likely regarding why no large rear window on the Mk I cars, as you indicate...and why I wasn't finding any! I knew something didn't make sense.
Ejey has bodies, or at least the rear panels, that are not original Mk I. 

Chuck, I realize that, but the original post was about a MK2+ Backlight (to use a British term). It would be very unusual for them to use a larger rear glass when the entire rear panel is in one piece.

Doc, Mk I and II rear side windows are the same size. Mk III was bigger.

Chuck, how would they do that, considering the entire rear panel is one piece? They would have had to re-tool and produce a rear panel with MKI bottom and MK2 window opening? Don't sound likely to me. Certainly would have been more likely if the rear window area was constructed like an Elf or a Hornet, in multiple pieces. Obviously, (because Elfs and Hornets) continued with the smaller rear screen they didn't run out of the smaller glass.

Hugh, I suspect Steve is referring to the later single bolt subframe mounts rather than the seat crossmember.

My guess would be corrosion or impact repair.

And back to Ejey.
  For some reason I seem to remember that the late runs of the Mk I S had the bigger rear window, but I can't find anything to prove it, so far.
  I do remember that at least some of the late runs did have the horrible, MkII rear side windows.

Steve, is the area around the windshield and rear window flat or recessed? The early style seats and crossmember would have been long gone by the time they built the first Cooper S. What you probably have is a 50 or 60 shell with a Cooper S VIN tag. Does it have shoulder harness mounting points? If so, where are they located on the B pillar? High or low? How about the front skirt? is it a full skirt or have the cutout areas to cool the disc brakes? What type of sunvisors does it have? Is there a small square hole about midway across the door opening (in the metal body just below the headliner) at the top? What year Cooper S is it supposed to be? Lots of questions/answers might narrow it down.

If your cars have FE numbers near the radiator, I may be able to give you an approx build date.

Not to confuse things, I'm currently working on what appears to be a MK1 Cooper S. The rear glass is of the smaller type but the front cross member is the single bolt per side type. The tunnel is round but the gas tank has no provision for an early style strap. In fact, there is no strap at all but looks like the bracket for a late strap if there. The right side tank is correctly installed. What do I have? The Vin plate is no help. Steve (CTR) 

I don't think any Mk1s were produced with the bigger rear screen as the entire rear panel was updated for the Mk2 which included the bigger light units - be aware that more than a few American "Mk1s" may be much later cars with only an old VIN plate due to the 25-year rule...

Hi all iam fairly new to this forum. and this topic has probably come up a few times
iam looking at a few mk1 minis from the US both were built in 1967 one july and the other march but both have the larger rear screen which was introduced later that year, ok so far
i want to know if bmc did infact start to fit the larger rear screen earlier in 1967 than the official launch of the mk2 in october
i have traced the history on one of the cars and it appears to be the original body shell
thanks for reading  this and hopfully somone can shed some light on this