Hi True.
Lovely coat! and a wonderful label, of course. This looks mid 60s to me. This label started in 1960. Here's the blurb from the label resource:
"Major American designer, born in Noblesville, Indiana. Norell worked with Hattie Carnegie from 1928-1940. He then partnered with Anthony Traina in 1941 to form the firm Traina-Norell, where he remained until Traina's death in 1960.
Anthony Traina was, for years, Norman Norell's backer. He died in 1958. At that point the Norman Norell label (without the Traina name) appears. Prior to that everything is marked Traina-Norell - back to the 1940s.
In 1960 he formed his own company, Norman Norell. Norell used a basic repertoire of shapes, yet achieved a great deal of variety. He was known for the waistless chemise dress, his "mermaid" sequin sheaths, the pussycat bow, and for making day sportswear shapes in evening fabrics and doing up sport fabrics for evening. Also known for his precision tailoring, he favored the finest imported fabrics, and thought it better to have one really good but threadbare dress than a wardrobe of cheap clothes.
Gustave Tassell took over the design house after Norell's death in 1972. During this time, the label reads, "Norman Norell by Tassell". The company closed in 1976. "
Courtesy of pastperfect2