A formal script cast on angled bodies, [Schröder] issued by Deberny & Peignot in 1928. [Reichardt] Accompanied by traits de plume (“pen strokes”) drawn by Alfred Latour. [specimen] It’s not clear if Latour worked on the letterforms, too.
Among digital fonts, OPTI Excelsior Script comes close, but doesn’t match a showing in a post-1950 specimen in all details.