This set of initials is an early creation (#0387) by Photo-Lettering, shown as Curfew Initials [PLINC 1960]. Listed as “original handlettered design” [PLINC One Liner 1971]. Apparently based on an alphabet drawn and engraved by Jules Girault and reproduced in his Album graphique from 1867. Lettergraphics has another interprtation of this design as Curlycue Caps [1969 specimen].
Uncredited digitizations include Clairveaux (Scriptorium) and Xyla (Intellecta Design, used for sample).