It is one of the longest-running mysteries in the art world, with collectors and experts at loggerheads over whether a centuries-old painting really is of Jane Austen.
But now it seems the row over the infamous Rice portrait may be coming to a close, after an accidental find at an auction cast more doubt on its authenticity.
For a stamp discovered on the back of a simple £400 painting titled “Mrs Smith” - picked up dull and unvarnished just over 18 months ago at a country auction - provides a match with the one on the disputed portrait.
If one is talking about proof, then the William Legg stamp certainly provides as much proof as we are likely to find
The marking, said to belong to an art supplier at the beginning of the 19th century, has opened up fresh questions about the provenance of the Rice portrait.
One expert has claimed the stamp near-enough proves it cannot show a young Austen as it does not hail from the right period.
The finding follows years of dispute about who the Rice portrait, named after its current owners who are sixth-generation descendants of the author, really shows.
The full-length portrait, which depicts a teenage girl in a long white dress carrying a green umbrella, is believed by some to be of the author when she was 13, painted by Ozias Humphry in the late 1780s.
It is unsigned and undated. If authenticated, it would be the only oil painting of Austen to exist.
But experts - including those at the National Portrait Gallery - are not convinced and, in 2007, when the portrait was put up for auction at Christie’s in New York it failed to sell.
The latest dispute involves a small stamp reportedly discovered on the Rice portrait, which reads Wm LEGG, High Holborn. The stamp is the similar to one on “Mrs Smith”, which was discovered by Anjana Ahuja, a journalist.
Ms Ahuja, writing in the FT Weekend Magazine, revealed she wrote to Jacob Simon, a former chief curator at the National Portrait Gallery who now volunteers as a research fellow, to find out about the stamp.
He believes it is linked to a “colourman” called William Legg who worked from High Holborn between 1801 and 1806.
Other canvases bearing the stamp - including the Rice portrait - would also have to be from this period, he said, which would make it too late to be of a 13-year-old Austen.
“If one is talking about proof [it is not of her], then the William Legg stamp certainly provides as much proof as we are likely to find,” Mr Simon said.
A spokesman for the National Portrait Gallery confirmed Mr Simon had examined the “Mrs Smith” portrait.
At this time, Jane Austen would have been in her mid-twenties and not the young adolescent depicted here
National Portrait Gallery
He said: “The colourman’s tax stamp on the back of this portrait of Mrs Smith, signed and dated 1803, adds further weight to the dating of the Rice portrait as circa 1802-5 due to the fact that it too has an equivalent William Legg/High-Holborn/Linen stamp on the back of its canvas.”
On the Rice portrait, he added: “The National Portrait Gallery acknowledges that it remains possible that the girl depicted here is Jane Austen, and naturally we would be delighted if it could be proven to be her.
“Nevertheless, we continue to believe that the stylistic features of the portrait, and the colourman’s stamp on the reverse of the canvas, suggest a date of about 1802-6.
“At this time, Jane Austen would have been in her mid-twenties and not the young adolescent depicted here.”
But some remain hopeful. The official website for the Rice portrait disputes what the stamp says and adds that it could of been a different William Legg.
Anna Rice, the current owner of the portrait, told the paper she has "no doubt" the portrait is of Austen.
But she added: "I very much welcome all debate on the subject and I also welcome any opportunity to bring the picture into the public domain."