Although the hairstyle raises a question as to the date, this is believed to be Charlotte Douglas at the time of her wedding in 1830. In that case it would be probably be painted by William Douglas who died in 1832.
However, the pose seems to have been copied for a later miniature by Archibald Ramsay Douglas, as the frame is almost identical to that shown in the signed example shown earlier and belonging to Claudia Hill. Also the pose is also very similar, similarly see her right hand, the ermine fur, the archway and the draperies.
It is very large for an ivory miniature at 190 mm x 135 mm. 12