A rare watercolor of the Brontë sisters is scheduled to be auctioned on Thursday by JP Humbert Auctioneers in England. The painting was originally set to be sold last month, but was pulled at the last moment as auctioneers tried to establish a more direct link to the supposed artist, Sir Edwin Landseer. The painting had been previously attributed by the National Portrait Gallery after four years of research by the vendor, but the auction house wanted to make certain that the link between the artist and the Brontë sisters was as solid as it seemed. John Humbert, of JP Humbert Auctioneers, says that experts have now confirmed the painting was done by Sir Edwin Landseer and is strongly believed to be of the famous sisters. "We have spent quite some time trying to establish a link between Landseer and the Brontes and after cross referencing with other known pictures by Landseer, we are confident that we have a strong argument that this picture is as important as we hoped," Humbert said. Mr. Humbert went on to say that thre has been international interest in the item and it is expected to raise between £20,000 and £30,000 ($31,580-$47,370).