https://www.ebay.co.uk/itm/196066538193
The rounded back case does not look like a 2652 - but exactly like my fab. Suisse 2648 (seen here) - only my back case does not look like it had been under attack!
1. Could it be a french or Dennison-like case?
2. Do you agree that the photo shows a mangled back case?

 

Definitely a mangled back case, but it could have that round curvature through overpolishing. IMO, it's not a snap-back caseback.

 

A French case wouldn't have the 2652 reference inside but just a French case number and the old style logo.

This just looks totally overpolished to the extent that the notches have virtually disappeared.

These are all 2652 case backs, 2x 14kt and 2x 18kt.

 

Not to be too picky, but could you rotate the casebacks on the first three so that the observatories align with #4 please?

Only for the photo though, you can re-tension them after.

 

You're absolutely right Jim, I've been having sleepless nights over this photo for years.....I'll get the DSLR and tripod out over the weekend....

 

You are right, now I see that it in fact does have screwback recesses.