I was watching the first episode of Mob City, set in 1947, and spotted a pen. I almost missed it -- guy lights a cigarette and then whips out a black "51" and writes on the matchbook cover. Correct pen for the period.
Episode 1, about 7 minutes in. Check it out if you're a Parker fan.
Episode 1, about 7 minutes in. Check it out if you're a Parker fan.