Portrait of a Pompadour lady Vintage Brooch

The trombone clasp places this brooch as 1930's-1940's vintage with the portrait of a much earlier lady  under perspex with a gold coloured frame, signed Jan. The back has been painted gold at some stage. Overall dimension is 5cms x 4cms. A little wear commensurate with age but nothing that detracts, and gift boxed by Vintageonline.