In these the nose is perfectly straight, whereas in the photograph [of the portrait] it is decidedly “retroussé”, and I can trace no resemblance in the other features.’

The painting was researched by art historian Bendor Grosvenor and social historian Emma Dabiri in 2021 as part of the BBC TV series 'Britain’s Lost Masterpieces' (aired BBC Four, 7 February 2022) and he believes the portrait may in fact show Anne Luttrell (1743–1808), who controversially married Prince Henry, Duke of Cumberland and Strathearn, the younger brother of George III, in 1771 – she was a commoner, not a member of the royal family or even aristocracy, and previously married. Her family were seen as political opportunists. Horace Walpole cruelly wrote: ‘her coquetry was so active, so varied and yet so habitual, that it was difficult not to see through it and yet as difficult to resist it.’ Their marriage resulted in the Royal Marriage Act (1772) which prevented future descendants of George II to marry without the permission of the sovereign. The portrait may relate to a finished portrait of the Duchess by Reynolds at Waddesdon Manor (exhibited at the Royal Academy in 1773), perhaps a preparatory study or abandoned alternative composition (x-ray shows that her left arm was once raised to her face). However, the eyelids and brows of the sitter in Glasgow Museums' portrait do not appear to match those in the Waddesdon portrait.

The painting came into Glasgow Museums’ collection in 1856 as by the society portraitist and founder and first President of the Royal Academy of the Arts in London, Sir Joshua Reynolds (1723–1792), but its attribution was later questioned. Investigation by conservator Simon Gillespie and his team for 'Britain’s Lost Masterpieces', in consultation with Reynolds specialist Rica Jones, has confirmed that the painting is indeed by Reynolds. Dendrochronology, a scientific dating method, confirmed the age and type of wood as mahogany. Although Reynolds usually painted on canvas, he did sometimes use single large planks of mahogany like this one.

Microscopic cross-sections of the paint revealed numerous complicated layers of pigment and very discoloured varnish. A sample taken from the earlobe shows five paint layers including lead white, cinnabar, red ochre and ivory black – all pigments Reynolds used. Linseed/poppy and walnut oil were also present which is consistent with Reynolds’ technique. It is evident that paint had been applied directly to the mahogany without a ground layer and weak boundaries between pigment layers suggest a rapid, wet-in-wet painting technique. All this is consistent with Reynolds' experimental practice.