A series of scribbled notes in the margin of a book found in the British Library is the latest proof that Shakespeare copied lines from Italy’s greatest poet, Dante, a group of literary sleuths have claimed.

The handwriting in the ancient copy of Dante’s Divine Comedy, which has sat on a shelf at the library for centuries, “is the first material confirmation that Shakespeare took words, themes and even characters from the Divine Comedy”, said the Italian author Francesco Sorti.

Dante’s 14th-century description in three parts of imagined journeys to heaven, purgatory and hell is Italy’s best known literary work but was not translated into English until 1782, more than two centuries after Shakespeare was born.

Contemporaries of the Bard knew the work but it had never been seen as a big influence on his plays.

What is known is that Shakespeare is likely to have read two Italian-English dictionaries, including words coined by Dante, written by John Florio, an Anglo-Italian writer and translator who moved in the same 16th-century literary circles as Shakespeare.• Shakespeare ‘would turn in his grave’ over theatre demolition orderDante’s word “inciela”, meaning “place in heaven”, is translated as “ensky” in one dictionary and used by Shakespeare in Measure for Measure.Florio’s copy of the Divine Comedy was lost — along with his entire library — but has now been discovered by Marianna Iannaccone, a researcher at the University of Insubria in Italy who has been hunting the library for ten years.The researcher who found the book said she “nearly screamed” when she saw it“We knew Florio owned it and an American researcher found what year his copy was printed and by who. I then found a copy at the British Library matching that description, and I realised the handwriting inside was Florio’s,” she said.The British Library has now confirmed the discovery after a handwriting expert reported it was Florio’s hand.“I nearly screamed when I discovered the book, but couldn’t because I was sitting in the British Library,” Iannaccone said. She saw Florio had underlined words in the Dante edition that he then put in his dictionaries — but there was more.• Meet Shakespeare the Shoreditch hipster, as his astonishing lost theatre is unveiledIannaccone showed pages to Sorti and his wife, Rita Monaldi, who have written extensively about Dante and Shakespeare, helped by their daughter, the historian Teodora Sorti. They noticed Florio also highlighted entire lines and scenes in the Divine Comedy that appear in Shakespeare’s plays, suggesting Florio fed ideas to the Bard.In one highlighted section, Dante compares fleeting fame to “worldly rumour”, writing: “Worldly rumour is nothing but a gust of wind, first blowing from one quarter, then another, changing name with every new direction.”Florio highlighted certain sections and commented on othersSorti pointed to the character called Rumour in Shakespeare’s Henry IV, who boasts: “Which of you will stop the vent of hearing when loud Rumour speaks? I, from the orient to the drooping west, making the wind my post-horse, still unfold the acts commenced on this ball of earth.”Sorti said: “The fact that Florio marked this long passage, of which there is no trace in his dictionaries, is a clear indication that it was selected for Shakespeare’s text.”• Shakespeare gets credit for women’s words, claims Susie DentFlorio also highlighted a section in which Dante discusses his determination to be virtuous: “I restrain my wits which I am not accustomed, so that it does not run without virtue guiding it.” That, Sorti said, inspired Shakespeare’s line “since my desires run not before mine honour” in The Winter’s Tale.“Florio also highlighted characters and themes which cropped up in Shakespeare,” said Sorti, who will list them in a new English edition of his and Monaldi’s book Shakespeare’s Dante.“We know people who knew Shakespeare were aware of Dante, but this is the first material confirmation someone in his circle owned the Divine Comedy and the underlinings are key,” Monaldi said.Sorti said it was possible Florio knew the playwright and translated and passed him his favourite passages of Dante. Both knew the poet Ben Jonson and Shakespeare dedicated poems to the Earl of Southampton, who employed Florio as his secretary.Scholars also believe Shakespeare read and was influenced by Florio’s translation of the French philosopher Michel de Montaigne.“Florio was a huge link between Renaissance Italy and England, and now between Dante and Shakespeare,” Iannaccone said.