By the strict definition of a sidelock having the mainspring attached to the plate and behing forward of the cock, I would say that the T&S is some hybrid of the A&D which they perfected possibly with the aide of Ernst Funk, son-in-law of F.W. Kessler. I'd like to see the plates removed on this one with the Funk safety: http://www.bobjonesguns.com/details2.asp?id=4492S

Some early Sauer's had the appearance of a sidelock but were also some type of hybrid.

Kind Regards,

Raimey
rse