This miniature portrait is inscribed by hand on the reverse; "Charlotte Stuart wife of (b 1810's - d 1853) William Stuart writer to the Signet Edinburgh. Mother of our grandfather William Stuart, Judge of the Native Land Court of New Zealand. Painted about 1825 by her father, William Douglas miniature portrait painter for Scotland to Princess Charlotte & Prince Leopold, afterwards King of the Belgians".
However, the writing is by a later hand and not by the artist. The birth date of Charlotte is probably 2 May 1810 in Edinburgh, daughter of William Douglas and Charlotte Grieve.
Charlotte married William Stuart on 4 July 1830. As her eldest son, William was born 6 Oct 1833 and appears to be aged about three in the painting, the portrait cannot be by William Douglas, as he died in 1832.
It seems it must instead be by Archibald Ramsay Douglas.
Further uncertainty is posed by the sketch shown here. This is an identical pose, but with the female sitter wearing Regency clothes and with a Regency hairstyle.
This sketch comes from the sketchbook of William Douglas and must be of some other sitter.
The most likely explanation is that Miss Douglas decided to copy the pose from her father's sketchbook, some years later when painting a portrait of her sister and her nephew, and modified it to show clothing and hair appropriate to the time when the portrait was painted. 2