The above page mentions that "This case also alludes to the purpose of the miniature, which has been further personalised by a lock of hair in the reverse, as Mr. Russell probably carried it when the couple were apart."
However, my friend Katherine was at Huntington Gardens, and noticed that there was a portrait of a woman with a miniature on her lap that looked a lot like Mrs. Russell above. Then I realized that not only had I seen the painting at Huntington Gardens, but I'd taken a close-up of the miniature and never connected her with Mrs. Russell. But it turned out they are very much connected. And that perhaps it wasn't Mr. Russell who carried the miniature, but Mrs. Russell's sister, Margaret.
Meet Margaret. She was painted in 1787 by Richard Cosway:
And my close-up of the miniature:
According to the Huntington Gardens website, the portrait is of Margaret Cocks, and that "She remained close to her sister Mary following the latter's marriage to William Russell." So Mrs. Russell is Margaret's sister Mary! And thus that's definitely her in the miniature in the painting of Margaret!
The link from Huntington also has more info like that Margaret is being painted like the classical "Melancholy." Though they seem to think the painting was done in a time of separation perhaps commissioned by Mary. However...
It turns out Mary died in 1786. Richard Cosway did this painting of Margaret in 1787, the same year the above portrait was done. Note the urn inscribed 'M.R./1786 'and the pedestal 'R.C.'
The V&A page says, "Margaret Cocks (1773 -1847) was the daughter of Joseph Cocks. Her father died before she was two and her much-loved older sister, Mrs Mary Russell, when Margaret was 13. She is shown here mourning at an urn containing her sister's remains."
So sadly it appears my Mrs. Russell died in 1786. I imagine she was quite young, but I don't know what year she was actually born.
In any case, Mary was gone by the time Margaret was painted with her miniature in the Huntington portrait by Cosway. So it's pretty clear Margaret was indeed separated from her sister and still mourning her.
I also learned that Mary had a daughter, also named Mary. Margaret was painted with her niece by Joshua Reynolds in 1789 when little Mary was 6.
It's also possible this was the last painting Reynolds did before he went blind.
I also learned that Mary Russell was also painted by Gainsborough in 1782, but it's in a private collection. The painting is apparently titled "Mrs Russell of Powick". I'm having no luck finding it, probably because it is in a private collection. This book has information about the painting: http://books.google.com/books?id=DAjHam
The book, called Kenwood, Paintings in the Iveagh Bequest, by Julius Bryant, talks about the above painting, which gives Margaret's birth and death dates (1773-1847) and little Mary's birth and death dates as well (1783-1806, though it goes on to say that Mary married the Revd Henry Domvile in 1806 and gave birth to their only child in 1811, which is contradictory to an 1806 death date.).
It also says that Mary Russell the elder was married to William Russell of Powick Court, Worcestershire, and mentions the Gainsborough painting. At this point Margaret was still unmarried, but she married a Joseph Smith of Shortgrove Hall in Essex, some time after his first wife died in 1791. He was Private Secretary to the Prime Minister Wiliam Pitt the Younger.
I put a little timeline together:
Mary Cocks born: ?
Margaret Cocks born: 1773
Mary Cocks marries William Russell: ? (Mary and William Russell are of Powick Court, Worcestershire)
Mary Russell painted by John Smart: 1781
Mary painted by Gainsborough, "Mrs Russell of Powick" - 1782 In private collection of family of Edward Cecil Guinness
Mary has a daughter, also named Mary: 1783
Mary Russell the elder dies: 1786
Margaret painted by Richard Cosway (twice, one large, one miniature): 1787
Margaret and 6 year old Mary Jr. painted by Joshua Reynolds 1789
Mary Jr. dies: ?
Margaret dies: 1847 after a long life, many children and grandchildren, is 2nd wife of Joseph Smith
But there is more! Another google search turned this up... I found out that a Francesca Cullen painted a copy of the Gainsborough portrait of Mary in 1888. It was auctioned at Christies.
There was no image, but the painting is described as follows: "Portrait of Mary Cocks, seated three-quarter-length, in a white dress with a black shawl, in a wooded landscape inscribed 'Mary, eldest daug of Jos. Cocks/first wife of Will./Russell of Powick/T. Gainsborough pinx/1782 (lower right) and inscribed 'This picture was painted from the original/in October 1888 by F. Cullen/of Bushey' (on the reverse)"
I did an ebay search to see if I could turn up the Christie's auction catalog, and I got lucky! I found the auction catalogue from March 1999 on ebay for 13 bucks including shipping.
The catalog came in the mail yesterday and indeed a photo of Cullen's painting of the Gainsborough was there! So here is Mary Russell in 1782. I don't know how good a likeness it is, but it's still really fun to see another portrait of her.
If anyone has seen this painting (or something that looks like it) somewhere else before, please post a link!
So ends my detective work on the lovely lady in green for now. I'm really happy that I was able to find out her name and that she was the subject of another portrait. I'm only sorry she didn't live longer.