Devised 2003 by Lara Friedman-Shedlov for Audrey McClellan's novel "The White Rose of Scotland," the
second in her trio of romance novels about life on the fictional island of Eilean Dubh.  
I believe the original deviser of the formation "petronella double triangles" was John Bowie Dickson, in
the dance "Pinewoods Reel."