It all started with a digitized photo of one of the irises that Gunnar
Andersson, a Swedish iris enthusiast, posted to Tom Tadfor Little's iris
web page. Gunnar did not know the name of his iris, only that it had grown
in his yard since the home was built, sometime in the early 1900s.
From photographic and corroborating evidence (Quick email to Gunnar; "Does your unknown iris have purple leaf bases?" Answer, "Yes!"), a HIPS ID expert gave the iris an 80% chance of being THORBECKE (Veitch before 1897). Thorbecke is not known to exist in North America and has not been grown as such since the 1950s. It was a very popular iris late 1800s/early 1900s but fell out of favor in the 1930s and disappeared from collectors gardens.
The nursery that introduced THORBECKE, James Veitch & sons, Mt. Radford, Topsham Road, Exeter, England; was among the most celebrated nurseries in England. Founded in 1808, it was owned by a succession of Veitchs and dealt in rare ornamentals. THORBECKE was an exciting development for its time and was pictured in Vick's magazine in 1898. (Volume 11, pg 382).
R. Wallace & Co. of Colchester, England featured THORBECKE in his catalog before 1897 and was still offering it in the 1921 catalog. It was described in the '21 catalog thusly: Thorbecke, very fine white standards, deep rich velvety purple falls, 2 1/2 feet tall. 9 pence each.
Bertrand Farr of Wyomissing, Pensylvania offered Thorbecke in his 1912 catalog and gave this description: Thorbeck [sic] Rich clear violet-blue amoena, reticulated white at the base, very handsome. 2 feet. 25 cents each.
Description from Cornell Bulletin 112, June 1925:
THORBECKE (Veitch before 1897) Color effect a white, velvety prune purple solid bicolor.
S. clear white, slightly overcast pallid violet. F. velvety prune purple, reticulated reddish brown on the haft. Beard fine, dense, projecting, orange colored.
Thorbecke is moderate in growth and has stiff, slender, deep yellow-green foliage, strongly tinged purple at the base. The blooms are fair sized, firm in texture, and clear colored. The flower is interesting for its clear color contrast.