Yes, he noted that.
Do you have a picture of the dial side of the movement (keyless works) and what is the diameter in millimetres?
It looks to be a Valjoux of some sort to my eyes.
Landeron 15.5''' is getting close.
However, we need to see the movement with the dial off (as in the lower picture) so that the shape of the keyless works can be seen.
These are like the "fingerprints" of a watch movement.
The style of the layout is almost generic and was used by many makers. Valjoux, Landeron, De Praz etc.