New light is being shed on a star painting in Tate Britain's new pre-Raphaelite exhibition after phallic symbols were apparently discovered in the work.

Pre-Raphaelites: Victorian Avant-Garde traces the 19th century British art movement led by Dante Gabriel Rossetti, William Holman Hunt and John Everett Millais.

Tate curator Dr Carol Jacobi is challenging the reputation of Victorians being repressed with a research paper on the painting Isabella (1848) by Millais in the show.

Can you spot the phallic symbols?

Her paper, to be published through the Tate, examines phallic symbols in the painting of two merchant brothers from Florence who discover that their sister has been having an affair with a clerk, Lorenzo. In the medieval story, retold in the Keats poem Isabella, the enraged brothers murder the clerk but Isabella digs up his body and plants his head in a pot of basil.

Dr Jacobi said that the shadow of a nutcracker, as well as the shape of one of the brother's legs, appears to be phallic symbols.

"It's not a one-off or a Freudian slip. It enriches our understanding of what is so hard to do in painting. It enriches our understanding of the characters," she said.

"This exhibition gives us the chance to look at it. Is it deliberate? If so, why would he have included it? It's quite shocking and unusual. It might be that the brothers are thinking about the desire and the dangers of desire.

"But more research needs to be done into how the Victorians saw what was Millais' first pre-Raphaelite painting."

Asked why the apparently phallic symbols were not noticed before, Dr Jacobi, whose paper is entitled Sugar, Salt And Curdled Milk: Millais And The Synthetic Subject, said: "When you look at a painting you have a story in your mind, so if something slips out you don't see it."

Dr Jacobi, who did not curate the Tate show, said another image in the painting, of salt being spilled, would have been familiar to Victorian audiences as a reference to a lack of sexual self-control.

The exhibition, which opens on 12 September, has been five years in the making and will also be shown in Washington, Moscow and Tokyo.

Andrew Lloyd Webber and Led Zeppelin guitarist Jimmy Page have loaned some of the 150 works of sculpture, photography, drawings and applied arts on display.

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• Michelangelo (1475-1564)

  Twenty years after painting the ceiling of the Sistine Chapel, Michelangelo sparked hot dispute with his enormous fresco, The Last Judgment. It depicted nudity on the chapel's alter wall and the Catholic counter-reformation critics were horrified. They deemed the work unfit for a papal chapel and after Michelangelo's death the offending genitalia were covered up. PHOTO: Artfinder

• Jean-Louis André Théodore Géricault (1791-1824)

  Géricault's monumental The Raft of the Medusa, depicted the aftermath of a contemporary French shipwreck in which the captain had left the crew and passengers to die. The painting ignited political controversy in Paris, fuelling widespread condemnation of corrupt authorities, but Géricault went on to become a pioneer of the Romantic movement - not bad for an artist who launched his career with a sinking ship. PHOTO: Artfinder

• Édouard Manet (1832-1883)

  Édouard Manet (1832-1883) - Édouard Manet caused a stir in the Paris Salon with his early painting The Luncheon on the Grass (Le déjeuner sur l'herbe). Showing naked women frolicking around fully dressed companions, they appeared to hold a mirror up to the prostitution problem that was rife in Paris' parks at the time - a taboo the city was not happy to confront head on. PHOTO: Artfinder

• John Singer Sargent (1856-1925)

  When the prominent portrait painter chose the beautiful young socialite Virginie Amélie Avegno Gautreau as a subject, she was delighted. But when the painting was unveiled to the public under the title Portrait de Mme *** the sitter's flushed ear and provocative loose shoulder strap caused a stir: Gautreau was humiliated and her mother requested the painting be taken down. Sargent renamed the piece to the more impersonal Madame X and repainted the dress strap to make it look more securely fastened. PHOTO: Wikipaintings

• Pablo Picasso (1881-1973)

  Picasso's Les Demoiselles d'Avignon was originally entitled The Brothel of Avignon. The women pose in primitive attitudes and the piece was deemed savage and immoral even by Picasso's supporters. Though it is now considered a revolutionary achievement, it remained rolled up in Picasso's studio for years after it was first shown. PHOTO: Wikipaintings

• Marcel Duchamp (1887-1968)

  Perhaps the most scandalous in Duchamp's string of provocative works was his porcelain urinal, signed 'R.Mutt' and entitled Fountain. When it was submitted for the exhibition of the Society of Independent Artists in 1917, it was rejected by the committee, despite the fact that the rules stated that all works would be accepted by artists who paid the fee. PHOTO: PA

• Marcus Harvey (born 1963)

  British artist Marcus Harvey found himself at the centre of scandal when his painting Myra was vandalised (with eggs from Fortnum & Mason) by angry members of the public when it was put on display at the Royal Academy of Art in 1997. It depicted the child murderer Myra Hindley in a portrait created completely out of the handprints of small children. The Sun said: "Myra Hindley is to be hung in the Royal Academy. Sadly it is only a painting of her". PHOTO: PA

• Marc Quinn (born 1964)

  When sculptor Marc Quinn's sculpture of pregnant, disabled artist Alison Lapper was unveiled on Trafalgar Square's fourth plinth, Quinn was highly criticised by disability groups for capitalizing on the shock value of disability. Many art critics described the piece as ugly. PHOTO: PA

• Damien Hirst (born 1965)

  As Britain's richest artist, Hirst is used to being under the spotlight and is no stranger to scandal. He has been accused of plagiarism on numerous occasions and was much criticised for his use of a baby's skull in 2008 piece, For Heaven's Sake. PHOTO: Wikipaintings

• David Blaine (born 1973)

  Not your traditional artist, David Blaine's world-famous endurance stunts have earned him a place in the history books. Whether it's being hung over the Thames, simulating drowning or being frozen alive, his particular brand of performance art has seen him called an illusionist,a publicity hound and a cheat. PHOTO: PA