Based on what I've found so far it is safe to say that this frame was built by Plume Sport, Edouard Teval's former employer. The "PS", followed by a four or five-digit number is typical for Plume Sport, including the jaunty angle at which the numbers have been punched into the BB shell. The serial number indicates it was built in 1967.

(Source: Plume Sport thread on Velo Retro Course)