Found a small stack of PDFs of scans of old issues of Grey Matter, Grey's research newsletters the agency sent out to media ("since 1935"). Particularly cool is a 1997 retrospective (pdf) of what Grey had published about television over the years.
From a 1946 issue:
"Throughout the still-raging dispute concerning the precise position television will occupy in the advertising firmament, a point has been missed... television is just one phase of a new advertising age (we might call) the "electronic age" of advertising...
We hope we will not be charged with being anti-newspapers, anti-magazines or any of the established media... but we see a brilliant future for radio, for television, for (other electronic media). And we would be sadly remiss in our duty to advertising... to clients.. to future clients if we did not firmly resolve to explore those new media intensively and utilize them to the maximum of their potentials."