You're correct, I have seen 'Caligula' - I've got the Arrow 4-disc box set
But there is so much controversy about the production of that film, does it count as '
a film directed by Tinto Brass'?
"In post-production, Caligula ran into plenty of problems and had seen repeated edits and re-edits even before it was released. Unhappy with director Tinto Brass' (who had also directed the equally explicit film Salon Kitty) original vision of the film, Guccione fired Brass and brought in other film editors like Giancarlo Lui, Russell Lloyd and Nino Baragli to edit multiple versions of the film, ultimately butchering the film's original Vidal screenplay beyond comprehension or repair. Guccione even went as far as to re-shoot some graphic porn material and spliced that into the final version. These added scenes include a girl-on-girl lesbian tryst that was edited in between the menage trois scene involving McDowell, Mirren and Teresa Ann Savoy and some modern looking—and totally out of place—hardcore material that was added to the infamous bordello scene towards the end of the film" Caligula (Four-Disc Imperial Edition) Review - IGN