Apparently some Bautte pieces from this collection are presently on display in Gallery 554. Maybe your friend could scout this out and see if there are plans to show the complete collection in rotation and perhaps some biographical info on the Lady?
The date of 1926 doesn't really provide any clues as to the motivation of our anonymous doner. Lady May Fletcher Moulton died in 1909 while her daughter Sylvia May lived much longer. The American connection is perhaps with Lady May's father, Major Alexander Henry Davis, of Syracuse, NY. He apparently had a villa in Naples and they travelled to the continent often, which is where May met Baron Fletcher Moulton who was an English peer and became is second wife.