In this document, released in September 1981, Jaeger-Lecoultre announces that "Jaeger Horlogerie" is taken over by the Saphir Group, merger of JLC and Favre-Leuba.
It is said that the "Jaeger Horlogerie" will soon be renamed in order to become "Jaeger-Lecoultre France".
It does not close the question about the commercial brand Jaeger that was used on clocks, but I think it remains a valuable information.
Regards,