"Alexander Douglass, Scotland Yard Detective," is, without doubt, a pseudonym. The author was apparently not English, for most of his stories have an American setting, and even those whose events take place in England show a decidedly American style of writing. "Douglass" wrote, during the 1880's, almost exclusively for Frank Tousey, and the name occurs among Beadle writers only as the author of one chapter in the composite novel "Jubilee Joe." It is possible, of course, that he wrote for Beadle under his own name as well, but this is at present unknown.
Beadle's Weekly. No. 128 (partim)
Half-Dime Library. No. 1090 (partim)
Popular Library. No. 43 (partim)