This recipe is a broad interpretation of Jacob A. Didier's 1909 original and the Casino recipes that follow in Hugo R. Ensslin's 1916 book and other subsequent...
The Didier/Ensslin recipe is more to my liking and reminds me much of my ideal Martini profile (orange bitters, lemon), just with a bit of added sweetness from the maraschino (and flavor) and the Old Tom (Hayman's). The orange juice and larger measure of maraschino in the main recipe here just seems to dilute the gin botanicals and intensify the maraschino beyond what I prefer. To each their own.
I've managed to find an earlier instance of the casino cocktail; on page 5 of "The Reminder" by Jacob A. Didier (3rd Edition) from 1909. It seems Ensslin copied Didier (the wording is almost the exact same).
3/4oz maraschino sounded like it would taste of nothing but maraschino so I went for 1/2oz and an additional dash of grapefruit bitters. Very nice, very soft, and even at 1/2oz the maraschino is starting to overwhelm. 8.5/10, HOF Challenge 7/291