Dante Gabriel Rossetti called his smouldering red-haired nude Venus Verticordia – Venus the heart turner – and she did just that, turning the critic John Ruskin away from his friendship and admiration for the artist.

“Ruskin said it was the roses he objected to, but I think it’s clear it’s the heady sensuality of the picture he couldn’t cope with at all – it’s well known that Ruskin had a problem with nudes,” said Simon Toll, a specialist at Sotheby’s, where the painting will go on sale in December.

“And there’s no doubt that the roses are very fleshy, like the licking tongues of the honeysuckle, which is just how Rossetti wanted them.”

Ruskin’s troubled sex life is the focus of Effie Gray, a new film written by and co-starring Emma Thompson. About to open in London, it charts his disastrous unconsummated marriage. There are various versions of the story, but some believe he was revolted by Effie’s body hair – so different from the marble classical nudes he had admired. She left him for the artist John Everett Millais, and they had eight children.

Rossetti had taken particular trouble over painting the flowers, including having out-of-season roses shipped from France.

Ruskin said nothing about the naked breast in the piece but savaged the roses, describing them in a letter to the artist as “awful in their coarseness”. Another friend, Graham Robertson, responded: “Of course roses have got themselves talked about from time to time, but really, if one were to listen to scandal about flowers, gardening would become impossible.”

Facebook Twitter Pinterest Dante Gabriel Rossetti, right, arm in arm with John Ruskin as William Bell Scott looks at them. Photograph: Hulton Archive/Getty Images

The painting is a watercolour version of an oil painting in the collection of the Russell-Cotes Art Gallery & Museum in Bournemouth. Rossetti had already sold the oil painting when William Graham, the Glasgow industrialist and MP who was a major patron of the pre-Raphaelite artists, admired it, and so painted him the watercolour.

The model was Alexa Wilding, whom Rossetti stopped on the Strand in London, fascinated by her beauty. He eventually persuaded her to model and even invited her to spend a Christmas at his shared country retreat, Kelmscott Manor, with his mother and sister. However, he found her conversation so dull that he wrote he wished he could shut her in a cupboard except when he was painting her.

Wilding was regarded by the other artists as extremely respectable, and only Venus’s head was hers. The naked body belonged to a cook – described by a friend as a giant who was well over 6ft tall – who was persuaded by Rossetti to pose years earlier.

Simon Toll has researched Wilding, and says she tried and failed to become an actor, and had at least five children outside of marriage before starting a new life in South Africa with the youngest.

Venus Verticordia will be on display at Sotheby’s before the auction in December, when it is predicted to sell for up to £1.5m. It will be the first time the painting has been seen in public since 1886, when it was sold from Graham’s estate. The estimate may prove conservative, as record prices have recently been set for Rossetti’s work, including a pastel of the goddess Proserpine, which sold for £3.3m last November, double the pre-sale estimate. A month later an oil painting, A Christmas Carol, fetched £4.6m.