Marshall McLuhan (1954)
It's clear to me that McLuhan was a big fan of early Harlequins. Well maybe not so clear but given the above it's likely he saw and picked up a Harlequin or two at the news stand or drug store around the corner from where he lived or down the street from his University office.
Here are few from 1954 he may have seen.
Harlequin 267 - Janaury 1954
Harlequin 275 - February 1954
Harlequin 302 - June 1954