Lady Emma Pennant, née Brudenell, was the daughter of Robert Brudenell (1769-1837), 6th Earl of Cardigan and his wife Penelope Anne, née Cooke (1770-1826). She married, in 1827, David Pennant (1796-1835) and they had a daughter, Louisa. Her brother was Lieutenant General James Thomas Brudenell, 7th Earl of Cardigan (1797-1868) who led the Charge of the Light Brigade.
The present miniature is most likely a marriage portrait. Painted in 1827, the year of the sitter's marriage, she is depicted wearing her wedding band.