This is how Andy Mariani describes it in his blue booklet:
Origin Luther Burbank. Mr. Burbank had given this plum, an exclusive variety, as a gift to Catherine Bunnell, wife of once prominent law professor Wm. Gorrell at Boalt Hall, Berkeley, probably in the early 1900s. The only known tree is still clinging to life in the backyard of the old Gorrell residence. CRFG was recently [in 1994] given the opportunity to save the variety by repropagating it. The plum is said to resemble Santa Rosa, which may be a descendant. The fruit is large, deep red to purple in color, ripening around July 4th. It had little commercial potential because the fruit ripened too quickly, the fruit did not keep well and almost all the stones cracked within the fruit; however, the plum was of such exceptional dessert quality that it was given to Burbank’s close friends as an enduring gift.
In hindsight, that name possibly dates to the CRFG propagation and could be synonymous with a variety mentioned in one of the older sources.