This painting portrays the eldest of the Honourable Thomas Harley’s five daughters, Martha. He was a wealthy banker and merchant, Lord Mayor of London, and the younger son of the Earl of Oxford. This portrait was probably made to commemorate the marriage of Martha to George Drummond in 1779. It was intended for Harley’s new residence built with the fortune he had amassed supplying the British army during the American Revolution. In this magisterial painting – the only full-length portrait by Gainsborough in Canada – the suave, fluid brushwork of the artist's late style enhances both the richness of the white satin gown and the pastoral charm of the park. To create unity between sitter and setting, Gainsborough enframed the young subject within the trees in the background and gently silhouetted her head against their greenery.