The 6 cil. 4 valve Basse & Selve aero engine (1919) produced 275 bhp. The semi-desmodromic valve gear with stirrup-type camfollowers (Delage-like) actuates rockers.
The system should ONLY have been fully desmodromic in case both the stirrup pin to rocker and the valve rocker connection would have been present.
This is not the case as the pictures make very clear.
Source: Jane’s all the world’s aircraft, 1919 (1969 reprint)
[Classification = Group 4]