Artist ID and value needed

A very old picture under glass that has a signature in the lower left corner of A.Th (printed not in cursor).I thought that more of the signature would be revealed if I removed the glued to the frame paper backing and carefully removed the picture; however, that is all that is in the corner. I was very surprised to discover that the drawing is actually done in chalk.Anthony Thieme sig is close but haven't found anything to show he used a shortened version.