I M Chaney Antique Furniture has dated this piece to the 1800s.
The frame is also signed by
B L Bielfeld

Peter Babell, Long Acre, near James St, London 1763, James St by 1768-1771. Papier mâché frame and ornament maker.
The painting is unsigned but previous painters of his portrait were George mendes and sir Henry Raeborn
Painting measures
25 x 30
Frame measures
32 1/2 x 37 1/2 inches
I M Chaney Antique Furniture has dated this piece to the 1800s.
You can view the stock and full dealer information on the I M Chaney Antique Furniture Profile Page