Thonet Bent Wood chair 1940s-60s

Michael Thonet invented the bentwood furniture process in the 1840s. This is a cushioned ladder back side chair from between 1943 and 1963 judging from the “New York 16” postal code (today’s 10016 zip code) and a postcard photo of the Brussels Restaurant that was at 54th Street and Park Ave in Manhattan, which used to own the chair, showing it in its former setting. Any info to further pinpoint a date is appreciated