In researching an unrelated EL&U answer, I came across this commentary in an item titled "Hobart Town" in the Sydney Gazette and New South Wales Advertiser (November 10, 1829):
These three journals—the Courier, the Colonial Times, and the Tasmanian—are all conducted in a very respectable manner.
The first made us laugh most heartily by the novel and utterly outré practice lately adopted by its Editor, of speaking in the first person singular! We believe it is without precedent or parallel in the whole history of newspapers, at least within the last hundred years ; and it looks and sounds so exquisitely odd, that it is difficult to persuade one's self the worthy Editor is not quizzing. Perhaps he has in his eye the example of the Spectator, and the similar diurnals of the eighteenth century : it is at all events a bold defiance of fashion and immemorial usage.
This item makes a couple of interesting points about the "editorial we": (1) it was (in 1829) so thoroughly established that the use of first-person singular by the editor of the [Hobart] Courier struck the author of this article as "novel and utterly outré"; and (2) its dominance as a journalistic convention was of such long standing that the author of the item could not think of a single countervailing instance "within the last hundred years."
I have two questions on this subject:
Assuming that the convention is not primordial, when did use of the "editorial we" first arise in English journalism?
To what extent was the [Hobart] Courier editor's use of the "editorial I" something new under the British Empire's unsetting sun, and to what extent did it reflect an earlier style perhaps discernible in Addison & Steele's Spectator or other early periodicals?