Quiet Street Antiques of Bath has dated this piece to the Georgian era.
A later inventory date of 1897 can also be seen on the back. Dimensions: 11.25 x 9.25ins (28.5 x 23.5cms).

This appears to have been copied from an original picture by the famous miniature portrait-painter, William Hoare, also of Bath, who was considered to be the leading portraitist in Bath until the arrival there of Gainsborough around 1760.
Quiet Street Antiques of Bath has dated this piece to the Georgian era.
Fine antiques at sensible prices
You can view the stock and full dealer information on the Quiet Street Antiques of Bath Profile Page