I am no expert on this but Mr. Harrison's site
http://www.antiquecameras.net/heliarlenses.html
Has an excellant summary.
Briefly, the first iteration f4.5 was in 1900.
A slightly improved version was patented in 1902
In 1903 and new version was introduced as the Dynar f6.
This version was tweaked in 1925 to be a f3.5 Heliar.
Later f4.5 variations were the Dynar design as well.
A variable softness version was the Universal Heliar.
A colour Heliar was created for smaller formats (1949)
Depending on size, a Heliar f4.5 (for the first 20 years at least) could be any of the 1900 design, the 1902 design or the 1903 Dynar design.
As to the Hirohito thing; I would like to read the original reference, There are plenty of news photos unlikely to be Heliars.
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