I searched one of the newspaper archives to which I have access and all results, except one, were ads for Braemar sweaters in newspapers from 1951 through 1960. The sole exception was a short 1972 article that noted that:
"Cashmere Sweaters Are Catching On" and "One fashion of the 1940s which is catching on again is the cashmere sweater. Started last fall by a few top designers, such as Halston, Bill Blass and Chester Weinberg, the cashmere sweater fits the trend back to more use of natural fibers. Old-time names in cashmere sweaters, such as Dalton and Ballantine, are readying groups for spring and next fall, while such Scottish names as Pringle and Braemar will be again heard from ..."
I wonder if you would find a designer label in your sweater if it was one of the later/early 1970s sweaters and that this is from the 1950s -- with replaced buttons. The label looks earlier to me, too.
Lynne