When did Mini door pockets change from or to the reinforced design?

Does anyone have any clues on this subject?

I have wrecked and seen many doors but none with those brackets maybe a owner installed for something

One of the doors on my Mk1 has those reinforcing brackets in the pocket. Both doors were used replacements for the rusted originals, bought from Warwick Agustin many years ago, so don't know what it came from. The brackets were a bit of a rust magnet, though.

I am repairing my door pockets, one has these brackets and the other does not; is it worth removing them to avoid the rust trap (as above) or do they serve another purpose?

Only guessing, but the extra brackets may have been intended to support the liner panel to sit flat in the bottom of the door pocket.
All later Aust'n doors seem to have deleted the brackets and the pocket liner panels don't sit flat in the bottom of the door but tilt slightly downwards towards the outside of the door.
Australian wind-up window design was based on the Morris 1100 set-up; the brackets may have been copied from their doors.

Thanks for your input guys.

Would thought one of you guros would have known.

BTW my door is in great condition.

Thank you for your response Bill, as it is not structural I may remove the brackets and keep the area clear to avoid corrosion, then just modify the liner so it sits flat.

That is an interesting point; I recently purchased some 1100 doors for parts to use on my doors and there are a lot of similarities, although nothing identical (so far) unfortunately. My door pockets were plastic on them, I am not sure if any had metal pockets? I had hoped the stainless door trims were the same, however the forms are slightly different. They are one piece though rather than with a joiner, is there any reason Australian doors were split at the top of the frame?