Need help dating antique garment

Migde, I think you're onto something. I just googled "1850s house dress" and look what came up:

 

my thoughts now: it's a dressing gown/ wrapper (adjustable morning dress) that used to have other kind of buttons only on the torso, and they were added later & the lace collar

 

If you have it there to handle, and feel the fabric is antique, then perhaps it is antique. My best guess is it is an early- mid Victorian wrapper that was re-worked into a costume. The lines of the pattern are a bit typical of wrappers of the time as well.

It is a lovely garment.

 

Thanks, everyone! After Barbara suggested the possibility it was a wrapper, I went and found many of the pics that Katarzyna found (thanks, Katarzyna!) and saw that many home garments had buttons (like Midge suggested). I am also thinking that it is a wrapper/house garment that was reworked. Based on the silhouettes/patterns I've found, my best guess is that it was originally 1870s/1880s.