This one is not actually my own attribution but I felt I had to share the opinion of an user of a site I used to frequent a while ago (Art Detective, super fun place, hope Art UK relaunches it), first because I highly agree with him, second I feel like I've found even better comparison pictures, and third it doesn't seem like many people have heard his opinion (and they need to!).
So I'll share it with the three people who'll (hopefully) read this.
The way Art Detective works is that someone will post about a picture from the Art UK website (official website for digital images of the UK's public art collections) looking for more information, this can be anything: date, artist, subject, provenance; and then the public (users of Art Detective) will offer opinions, once sort of a public concensus has been reached the manager of the site will decide if there is enough evidence and reach the museum that holds the specific work of art to see if they agree with the new .... anything (date, artist, subject, provenance, etc.).
On the 13th of September of 2016 a picture was posted to the site with the heading "Did Francis Cotes (1726–1770) paint this unidentified lady?"
The Cotes attribution was quickly abandoned, with people noting the seemingly earlier looking dress (1720s-30s as opposed to the decades when Cotes worked, 1760s-70s).
Attributions to Thomas Hudson, Joseph Highmore and George Knapton were proposed and soon abandoned due to differences in style.
Respectively Cotes, Hudson, Highmore, Knapton.
The discussion petered off and in 2023, when people were already suggesting its closure (and I believe around the time when Art Detective itself stopped working), a user by the name of Louis Musgrove made the suggestion of John Wollaston (British artist mainly known for his work on the colonies (US)).
Picture used by the user to illustrate the similarities "our sitter has a unusual smile and funny rings around the eyes.... This ladies dress is very similar in construction to our sitter. And the thick lines under the eyes. Just a thought "
The suggestion was mostly ignored by the community (including, I admit, me) who instead focused on affirming that it was part of the British school (some users had suggested a French origin), and with that the discussion ended.
Link to orginal discussion: https://www.artuk.org/artdetective/discussions/discussions/did-francis-cotes-17261770-paint-this-unidentified-lady/group/portraits-british-18th-c
Myself, I was not particularly won over by the suggestion. Years later (2025) I decided for completely unrelated reasons to take a look at the work of John Wollaston. And I found this.
1749 Lucy Parry, wife of Admiral Parry
Similar round faces with cow eyes and hieratic smiles, similar scoop necklines with separated breasts.
Similar hands and fingers, both resting on a surface!!!, similar depiction of lace.
Similar depiction of clothing folds.
Also Lucy's portrait (the Wollaston which more closely resembles our portrait) was painted before Wollaston left for the colonies, and it would make total sense for a portrait that was painted on Britain (as is most likely for a portrait in a British collection) to look more similar to other portraits from the British period of our painter.
It didn't immediately click, but once I had (again for completely unrelated reasons) taken another look at the whole discussion, the resemblance seemed unmistakable.
So I leave you here, much as Louis Musgrove said "just a suggestion". But if you do agree with Mr. Musgrove, be sure to make your agreement know to the authorities at Art Detective (if and when they come back obviously).