Red, the Clark crossdraw is visually reminiscent of the Hoyt crossdraws, albeit with a different spring configuration.
Another interesting aspect is the claim in the Clark advert that they shipped 800 shoulder holsters to the US Dept. Of Justice in the mid-1930s.
Yes indeed, the Hoyt is similar and has a wing under the belt but lacked the slot; the Clark actually has the slot in the wing -- what today we call an 'outboard' or 'trailing' slot -- and Bruce is incorrectly credited with thinking of that. The Clark even appeared in the 1950s TV show Dragnet.
We do have images of DOJ agents actually wearing some of those very shoulder holsters. Turnerriver originally supplied me with Hoover's personal order for four of these Clark shoulder holsters and the image is dated of them wearing them for that year (it was not the FBI then; it was the BOI) early 1935.
Also, be aware that Hoyt and Clark were buds. Both were from KS and Hoyt's original company in '29/'30 was as a sales agent including for E.E. Clark; and it was at the very same time mid-'30s that they both made the switch from leaf springs to wire-form springs; the latter used in the Clark 999 and of course in Hoyt's famous forward draws which nevertheless are not proposed in his patent for the wireform version of the shoulder holster.
Soon afterwards, in the '40s, Berns-Martin's shoulder holster used a wireform spring inserted in the manner of the Hoyt (from the mouth end) instead of the leaf spring of its Speed holster for the belt.
Another view of the Clark 999, which originated the reinforced mouth of the holster later seen on Nelson and Sparks (and Bianchi) holsters; Brauer did the same with their crossdraw of the era.
I understand that Bruce's widow Sandy, a former president of NRA, has authorized copies of his holsters by a maker who has Bruce's patterns. I can't imagine what positive could be accomplished from a revival of what has been copied many times including/especially by Milt Sparks; but hopefully she is being paid royalties (which she deserves) because the Sparks company has tacitly acknowledged that Bruce was not paid for the copies of his designs by Milt or the successor company. That seems wrong to me.