(never before) past perfect inversion

Point 68 in  PAST is defined as:

past perfect simple,  invert the subject and auxiliary verb after ‘never (before)’ to talk about a unique event, often in formal contexts.

This point also overlaps the categories of Negatives and Adverbs.

1 NEVER BEFORE HAD I SEEN 57

  The New York Review of Books

“I was floored,” she writes; “never before had I seen any human skin books that were so obviously of human origin.”

2 NEVER BEFORE HAD I FELT 19
3 NEVER BEFORE HAD WE SEEN 18
4 NEVER BEFORE HAD I EXPERIENCED 17
5 NEVER BEFORE HAD HE FELT 16
6 NEVER BEFORE HAD I HEARD 15
7 NEVER BEFORE HAD HE SEEN 14
8 NEVER BEFORE HAD THEY SEEN 9
9 NEVER BEFORE HAD I ENCOUNTERED 7
10 NEVER BEFORE HAD I THOUGHT 5