I don't know about the connection between Sauvageot and Gillot, Patricia, but I believe that La Maréchale Pétain is the title given to Maréchal Pétain's wife.

The Rose Annual, UK 1930 p169 and 1931 p215 lists 'Marechal Petain' at Trial Ground No. 152. This was a "blood red" and "blood red in bud, opening to cerise". The sender was F. Guillot / Gillot, France. I presume this was not the yellow/pink 'Marechal Petain' HT from Louis Reymond, 1926. It may have been that this Trial Ground No. 152 rose's name was later changed to 'La Marechale Petain' to distinguish it from the earlier yellow/pink 1926 rose. Was there a connection (breeder/introducer) between J. Sauvageot and F. Guillot / Gillot?