Australia was big on assembling CKD cars with lots of domestic content. This is an aftermarket fiberglass hardtop with vinyl cover that was manufactured in Australia. Notice the sharp corner on bottom edge outboard at back. This appears to run all the way out to position of the piping at body to wing joint rather than curving around on top of the body tonneau as is more common. So far the manufacturer's name is unknown. Due to normally warm and dry climate, MGA hardtops are fairly rare in Australia (as are MGA heaters).

I think these photos were from Larry Wheeler.

Addendum:   On 1/9/2010, Frans Henskens in Australia wrote:
"My car had a fiberglass hard top (made by J&S Fibreglass) with aluminium side screens".

So far no clue if this manufacturer name matches these pictures, but how many companies in Australia may have been making hardtops for the low production MGA when heaters were nearly non-existant and hardtops were not popular?