It is the Poang chair by IKEA. The early versions have the same tufted upholstery like your example but more common in fabric and dates back to the early 1970s designed by Noboru Nakamura and Lars Engman.
If you google its history, something should come up. It is the Poang 'de luxe' model and should never be confused with a Bruno Mathsson design.
I googled poang chair 1976 and some vintage ads showed up in the images.
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