I take it that you've never seen that operetta, nor any photos, drawings ( dear Gilbert's or anyone else's ), illustrations, or paintings of the show. IIRC there are many such on line and even on YouTube.
I have had the pleasure of seeing Iolanthe and ALL of the G&S operettas, many, many, many times over, except sadly, for the recreation of THESPIS; which I don't know WHY I wasn't taken to see ( the semi-professional troop that my parents belonged to did it ), but I wasn't.
And poor Strephon is only a fairy from the waist up; his bottom 1/2 is human. :-)
Oh I’ve seen a production of Iolanthe at the opening when they are dressed like that.I helped in the stage crew for that one....the humor of it was they threw in a few plump ones to sort of stomp around while the smaller ones were a bit more daintier in their opening...”tripping thithering”.(Produced a lot laughs when the fat ones came stomping through) A bit more lower cut and modest but still much like the clothing seen in posting 13. They used very shear and lacy material and flesh colored leotards or stocking for the legs. I don’t remember how they kept the wings on. This was Summer Savoyards “83 production of Iolanthe
I know Iolanthe very well, just listened to the Royston Nash 1972 D’oyly Carte version a couple of days ago.
Princess Ida is another favorite.