Inversion in “only [adverb] have they”
Is there some rule governing the following, or similar, subject-auxiliary inversions (*"Rarely they do see the light of day", *"Never I have been so insulted")?
In fancy sit-down restaurants, you can order a large meal and halfway through the main course, take a little dead cockroach or a piece of glass out of your pocket and place it deftly on the plate. Jump up astonished and summon the headwaiter. "Never have I been so insulted. I could have been poisoned" you scream slapping down the napkin. You can refuse to pay and leave, or let the waiter talk you into having a brand new meal on the house for this terrible inconvenience. (link)
Rarely do they see the light of day; it's generally judged to be in no one's commercial interest that they should. Just occasionally, however, like a seemingly dormant volcano, they explode into the open. (link)