Focus on La Bella Principessa and discuss the Opposition to Leonardo attribution.
The New Yorker article discussed the troubling circumstances in which Kemp attributed this work to Leonardo. But apart from this, strong indications are going against the hypothesis of authenticity, and the attribution to Leonardo has been challenged by a number of scholars who showed interest. Among the reasons for doubting its authorship are the lack of provenance prior to the 20th century – unusual given Leonardo's renown dating from his own lifetime, as well as the fame of the purported subject's family – and the fact that it was on vellum. Only once did Leonardo use vellum and old sheets of it are easily acquired by forgers. Leonardo scholar Pietro C. Marani discounts the significance of the drawing being made by a left-handed artist, noting that imitators of Leonardo's work have emulated this characteristic in the past. Marani is also troubled by use of vellum, "monotonous" detail, use of colored pigments in specific areas, firmness of touch and lack of craquelure. A museum director who wished to remain anonymous believes the drawing is "a screaming 20th-century fake", and finds the damages and repair to the drawing suspicious. The work was not requested for inclusion in the 2011–12 exhibition at the National Gallery in London, which specifically covered Leonardo's period in Milan; Nicholas Penny, director of the National Gallery, said simply "We have not asked to borrow it."Carlo Pedretti, one of the scholars who attribute this work to Leonardo, had before made a mistake attributing a painting from the twentieth century to him.Klaus Albrecht Schröder, director of the Albertina, Vienna, said "No one is convinced it is a Leonardo," and David Ekserdjian, a scholar of 16th-century Italian drawings, wrote that he suspects the work is a "counterfeit". Neither Carmen Bambach of the Metropolitan Museum of Art, one of the primary scholars of Leonardo's drawings, nor Everett Fahy, her colleague at the Metropolitan, accepts the attribution to Leonardo.Several forensic experts on fingerprints have discounted Biro's conclusions, finding the partial fingerprint taken from the drawing too poorly detailed to offer conclusive evidence. Biro's description of the print as being "highly comparable" to a known fingerprint of Leonardo's has similarly been discounted by fingerprint examiners as being too vague an assessment to establish authorship. When asked if he may have been mistaken to suggest that the fingerprint was Leonardo's, Biro answered "It's possible. Yes."  Kemp's later publications do not use the finger-print evidence in support of the attribution.
Noting the lack of mention of dissenting opinion in Kemp's publication, Richard Dorment, the former husband of Ganz, wrote in the Telegraph: "Although purporting to be a work of scholarship, his book has none of the balanced analysis you would expect from such an acclaimed historian. For La Bella Principessa, as he called the girl in the study, is not art history – it is advocacy."Fred R. Kline, an independent art historian and author of Leonardo's Holy Child--The Discovery of a Leonardo da Vinci Masterpiece: A Connoisseur's Search for Lost Art in America, is known for his discovery of "Leonardo's model drawing" of Infant Jesus (which has yet to be accepted by Leonardo scholars) and for a number of important discoveries of lost art by the Nazarene Brotherhood, a group of German painters working in Rome during the early 19th century who revived the styles and subjects of the Italian Renaissance. Kline has proposed one of the Nazarenes, Julius Schnorr von Carolsfeld (1794–1872), as the creator of the drawing. In evidence, Kline points to a drawing on vellum by Schnorr, Half-nude Female, in the collection of the Kunsthalle Mannheim in Germany, which he suggests depicts the same model, although older, as portrayed in La Bella Principessa.
Comparative material-testing of the vellum supports of the Mannheim Schnorr and La Bella Principessa were anticipated to occur in the New York federal court lawsuit Marchig v. Christie's, brought in May 2010 by the original owner of La Bella Principessa, who accused Christie's of breach of fiduciary duty, negligent misrepresentation and other claims. However, the court dismissed the suit on the ground that the claims were brought years too late (Statute of Limitations and Laches), and thus the merits of the suit were never addressed. The district court decision was upheld on appeal.Disagreements with the attribution to Leonardo were made before the discovery of the missing page in the Warsaw Sforziada book. No alternative attribution has been accepted by Kemp or his research group. Kline claims that no comparative scientific analysis has been made of the vellum supports in question: the Warsaw Sforziada book, the Mannheim Schnorr (an alternate attribution), and La Bella Principessa, although Kemp and Cotte have shown a close match between the vellum of the portrait and the book. Further analysis of the vellum could possibly provide the conclusive evidence that may support or disqualify Schnorr's authorship.
In November 2015, notorious art forger Shaun Greenhalgh claimed that he created the work in 1978, at the age of 20; Greenhalgh said the woman's face is that of a supermarket check-out girl named Sally who worked in Bolton, outside Manchester. In his memoir A Forger's Tale, written in prison, Greenhalgh claims as a 17 year old to have forged the drawing by obtaining an old piece of vellum from a reused 1587 land deed. Kemp said he found the claim hilarious and ridiculous.
Milan vellum Julius Schnorr von Carolsfeld Telegraph Fred R. Kline Warsaw provenance Albertina, Vienna Christie's art forger Leonardo da Vinci National Gallery negligent misrepresentation craquelure Vinci Kunsthalle Mannheim Carlo Pedretti Shaun Greenhalgh The New Yorker Albertina Italian Renaissance fingerprint Laches breach of fiduciary duty Nazarene Brotherhood forensic Pietro C. Marani lost art Statute of Limitations Klaus Albrecht Schröder Manchester Metropolitan Museum of Art Nicholas Penny