Hi Bob,

Thank you for contacting Mearto with your appraisal inquiry.
While a few paintings signed "M.STANLEY" have come up for auction, there is not much known about the artist, nor are they listed in AskArt.com, which is one of the authoritative artist databases we use. The artist is known for his Classical scenes, though your painting is the largest and most complex of those I've seen.
Based on the photos and information provided, and subject to examination, this is:

Continental School, 20th Century
Untitled (Classical Interior)
oil on canvas
signed lower right "M. STANLEY"
40 by 40 inches, in a parcel gilt and ebonized frame
CONDITION: appears to be in good condition
PROVENANCE: acquired at auction
$800-1,200*
*represents a fair-market value for auction purposes; retail or asking price may vary.

Please let us know if you have additional items to appraise, and thank you again for using Mearto.