A lost portrait of Admiral Lord Nelson's mistress Lady Hamilton has been discovered at a Lymington antiques shop.

The painting by Richard Westall shows Emma Hamilton gazing over her left shoulder, with her right breast exposed under a loose gown.

It is thought to have been painted in 1802, three years before Nelson's death at the Battle of Trafalgar.

The oil on canvas painting was taken to antique dealer Charles Wallrock of Wick Antiques in Lymington, Hants, by an elderly woman who had owned it for years.

Mr Wallrock carried out research on the item and confirmed it was one of four studies of Lady Hamilton produced by Westall. It is now for sale for £85,000.

Nelson first met Emma Hamilton in Italy in 1793 and in 1798 he returned to Naples as a hero following the Battle of the Nile.

There they fell in love and formed a relationship that Emma's husband Sir William is said to have encouraged given Nelson's status.

The three travelled around in a bizarre ménage à trois, which intrigued and scandalised British society, making Emma a huge celebrity.

She was a model and actress and was English portrait painter George Romney's muse and he painted her more than 60 times.

Mr Wallrock said: "It is a lovely painting of Emma in a classic pose as the Greek princess Ariadne and we have had a lot of interest.

"It has been lost and emerged last year when a private owner brought it to me.

"We have conducted research and of course compared it with the known black and white print. The frame also looks original.

"The three companion portraits show Emma as Sappho, which is in the National Museums of Liverpool, Saint Cecilia, which is in the National Maritime Museum, Greenwich, and as a bacchante, which is privately owned.

"They were all likely to have been completed following Emma's return to England in company with Nelson in 1800 and before the death of her husband Sir William Hamilton in 1803.

"A notable art collector who had previously encouraged and actively promoted portraits of his beautiful younger wife, Hamilton would have tolerated and welcomed images of Emma.

"Despite their classical staging, the paintings are highly sexualised with Emma displaying a naked breast in two of the four.

"This daring feature by such a celebrated and scandalous sitter would have titillated the contemporary viewer and was a detail denied to the other many other well-known artists who portrayed Emma, notably George Romney.

"At the time of the sittings, Sir William was aware of the sexual relationship between his wife and his friend Nelson and so the otherwise reticent

ambassador may have allowed his wife to be portrayed in a manner more familiar to a courtesan."