And he went by Charlie not Chuck.
Charlie Frost was an account exec on the AmEx account at O&M as you state (great that you found that out!). During the years I knew him (mid-late 1970s), Charlie would often come to our graphic arts studio on East 47th Street – a few blocks east of O&M’s headquarters at the time – to check on a job we’d be doing for his group. I remember him being a very down to earth, gregarious guy.
Our studio made 35mm slides and other presentation materials and O&M was one of our best clients along with a number of other ad agencies of the day (think Y&R, JWT, BBD&O, RS&L, Ammirati + Puris, etc).
On occasion Charlie’s wife (Barbara? I can’t quite recall darnit) would freelance as a typist for us. They were both really nice people. Barbara was quite a bit taller than Charlie BTW!
Thanks for the memory!
ETA: Link to column: Who is C. F. Frost, whose name appears on sample American Express cards? - The Straight Dope