The original style, probably used until January 1967, front stamped and screwed.
The second style, said to be used from January 67 to autumn 72 on UK cars, the 1970 model year for North American. This appears to be reverse-stamped (see the partial digit of the sequential number on the right), on a 69 MGC. Also pop-riveted, whereas Clausager says this didn't start until 1970.
The third style, used from autumn 72 or January 1973 on UK cars until the final year, reverse stamped (this is a 74 V8). Opinion is that reverse stamping came in with this plate ...
... however my September 72-built roadster has the old style plate, with the new style of stamping.
The final plate used for one year, with the extended chassis number prefix and the paint and trim codes. This is clearly front-stamped.
The North American additional strip-plate on the dash-top viewable through the screen from the outside, used from 1st January 1969
The special North American plate used from September 1969.
The Moss catalogue North American plates, with the correct date ...
... and the UK plates with the incorrect date for the change from one to the other
The 4-cylinder location, which doesn't seem to have changed until the final year when it moved to the bonnet lock panel on the same side ...
... and the V8 location