Original post here. This image was researched by Bacchus at ErosBlog as part of the “Δ commission.” The research was originally published at Infernal Wonders as “Δ 008 – Trench Coat Trouble.” Here is what Bacchus found.
Although little information about this photograph could be found, a version of it appears as the third of a three-image series at imagevenue (warning: hostile popups offering potentially-dangerous downloads) with URLS containing the name Barbara Capell:
http://img125.imagevenue.com/img.php image=72001_barbaracapellScan_141009_0001_123_140lo.jpg
http://img102.imagevenue.com/img.php?image=72003_barbaracapellScan_141009_0002_123_110lo.jpg
http://img171.imagevenue.com/img.php?image=72005_barbaracapellScan_141009_0003_123_835lo.jpg <<===
The first of those two links lead to scans of fragments of German language pop-culture magazine articles about Capell, who appeared in a number of pulpy movies and TV series in the 1960s and 1970s. Although she appears with dark hair in those black-and-white scans — and is characterized as a brunette in her entry in German Wikipedia — this screenshot of her from La Noche De Walpurgis looks like it could plausibly be the same actress as the nude tied to the chair:
The image of Capell (if it is indeed Capell) tied nude while men in trench coats point guns at her looks very much as if it were published in a pulp magazine in the adventure/detective style. Although no such attribution could be confirmed, Capell’s career did extend to magazine modeling; she even appeared on the cover of an issue of German Playboy in 1973.