@meggan-dwyergmail-com It's Slagelse Møbelvaerk, later production. I guess 60s but I did a quick search and didn't find another one. Kurt Ostervig drew many designs for them later on. It could also be an in house design or one of many other designers. Slagelse worked with a whole bunch.
"People buy a chair, and they don't really care who designed it." (Arne Jacobsen)
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