A hidden and mysterious painting of a masked woman and a large white mouse is to go on public display for the first time as part of the biggest Aubrey Beardsley exhibition for more than 50 years.

Tate Britain will show nearly 250 drawings by the artist, considered the enfant terrible of 1890s London. Beardsley is chiefly remembered for works that are as beautiful as they are strange and filthy.

It will also display Beardsley’s only attempt at oil painting. On one side is a work titled Caprice, a depiction of a woman being invited towards an archway by a man with dwarfism in a red outfit. The work has previously been on display. On the reverse, and making its public debut, is a painting of the masked woman and mouse.

“We don’t know who this woman is – it could be an imaginary subject,” said the Tate Britain curator, Caroline Corbeau-Parsons. “It didn’t enter the Tate collection until 1923 and we have never shown this side.”

Quite what was going on in Beardsley’s mind is open to speculation. “[His] mother called him ‘my little mouse’, so there have been lots of Freudian interpretations of the mouse in the painting,” Corbeau-Parsons said. “To me, it looks a decadent Mona Lisa, but I just don’t know.”

The staging of the exhibition was reason enough to have the painting cleaned and a special case constructed to allow visitors to see both sides, and perhaps interpret it for themselves.

Corbeau-Parsons said Caprice was painted under the guidance of Beardsley’s friend Walter Sickert. In Beardsley’s house in Pimlico, central London, the artwork was hung with the masked woman looking out.

The painting is more a curiosity than a great work of art, unlike the drawings that have been gathered for the biggest Beardsley show since an exhibition at the V&A Museum in London in 1966.

That show inspired several psychedelic artworks and album covers, such as Klaus Voormann’s famous creation for the cover of Revolver by the Beatles.

Though Beardsley died at just 25 he had packed a lot into his life, Corbeau-Parsons said. “He was constantly working. He loved to project this persona that he was an idle dandy and everything came easy to him, but he was actually incredibly hardworking.”

Beardsley is perhaps best known for his work with Oscar Wilde. He illustrated the author’s controversial play Salomé and was, by association, forced out of his job as art editor of the Yellow Book magazine when Wilde was prosecuted for gross indecency.

Corbeau-Parsons said there was so much more to Beardsley, and generations of people had not the chance to encounter his work since 1966. “The drawings are so beautiful, they’ve got incredible depth … they are almost three-dimensional,” she said.

Many are also sexually explicit, and the show includes content guidance. Some of the most erotic pieces have been gathered in a purple-walled “boudoir” showing illustrations for the ancient Greek comedy Lysistrata by Aristophanes.

Tate Britain’s director, Alex Farquharson, said Beardsley’s drawings had shocked and delighted people for more than a century.

“We hope this exhibition reasserts Beardsley’s pre-eminent position in late Victorian art, a position sometimes eclipsed by our own art history’s overwhelming emphasis on oil painting.”

• The Aubrey Beardsley exhibition will be at Tate Britain from 4 March to 25 May.

Artworks on the back of paintings

Francis Bacon’s Study For A Head (1952), from his Screaming Popes series. Six previously unseen pieces of his work (not pictured) were discovered in 2018. Photograph: Sotheby’s/PA

• A vibrant and unknown oil sketch by John Constable was found hidden under his oil sketch of Branch Hill Pond in Hampstead by V&A conservators in 2013. X-rays had revealed a ghost outline, which was assumed to be a sketch Constable had decided to paint over. To curators’ surprise and delight another sketch was found glued underneath.

• Incomplete works by Francis Bacon, part of his Screaming Popes series, were discovered on the reverse of works by the aspiring artist Lewis Todd. After Todd died in 2006, the story emerged of how Bacon gave him canvases with work he was not happy with. Todd painted on the other side but it was the Bacon scraps on the reverse that were together estimated at £100,000. Experts advised anyone with a Todd artwork to also look at the back.

• A Lucian Freud landscape, worth approximately £30,000, was discovered in 2018 beneath a landscape worth about £200 by the artist Tom Wright. It emerged that the pair were friends and Freud had given Wright the painting. Rather than admire it, Wright reused the canvas to create his own landscape. It took conservators nearly two years to scrape off his painting, flake by flake.