According to the Clan the Borthwick tartan in its current form has been worn since the 1950s.
Threadcount R/16 K8 N40 K56 N40 K8 R40 G/8
Borthwick
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The Borthwick dress tartan came about when Major John Henry Stuart Borthwick (later to become Lord Borthwick in 1986) asked Lochcarron to design a dress version of the tartan for special occasions and female members of the clan.
Threadcount DG/28 K4 R32 K8 W28 K8 W/16
Borthwick Dress