Here's one way to track it down:
Go to the list of Knoll designers on their site.
https://www.knoll.com/discover-knoll/designers
Open another browser window and do an image search for [name of first designer on list] chair.
Methodically copy and paste each designer's name into the search terms. If the chair was designed by an individual and not a committee, it could well pop up.
PS--I'm guessing that's a steel frame, not iron.
If you need any help, please contact us at – info@designaddict.com