A rare portrait of Princess Diana painted during the most turbulent period of her relationship with Prince Charles and the British press has been displayed in London for the first time after selling at auction in January for over $200,000.

The portrait was painted by artist Nelson Shanks as a preparatory study for a much larger formal painting of Diana which she later hung on the grand staircase of her Kensington Palace apartment.

The work was undertaken in 1994 which was a turbulent period in Diana's life coming just two years after her separation from Charles and three years before her tragic death in a Paris car crash.

The display of the portrait by British-based art dealers Philip Mould & Co. at the Masterpiece Art Fair in London comes as the first joint painted portrait of Diana's son, Prince William, and his wife, Kate Middleton, was unveiled in Cambridge last month.

The Shanks portrait of the princess shows her glancing downwards in what Philip Mould & Co. have called "quiet introspection."

"Diana's expression is strikingly honest and was perhaps considered too direct for the final portrait, which shows Diana in a less revealing, profile pose," the company said in a press release. "The final work is nevertheless a defining image within Diana's canon of portraits."

Despite being one of the most famous women on the planet during the 1980s and 1990s, Diana sat for relatively few official painted portraits with a notable example being a 1985 work showing the princess in three poses by artist John Merton commissioned by Cardiff City Hall in Wales.

Diana attended multiple sittings with Shanks at his studio close to her home at Kensington Palace in London and over this time the princess became close to the artist and his wife, Leona.

When the Shanks had moved back to America after their time with Diana had come to an end she wrote them a letter reflecting on the turbulence of the past year saying:

"I do miss you and Leona in London, as coming to the Studio was a safe haven, so full of support and love."

Speaking of the portrait, Mould said in a Masterpiece video: "Partly by accident, I think this is one of the most significant royal portraits done in the twentieth century."

"Princess Diana had gone almost as a form of refuge and as a sanctuary to the artist's studio," he added.

The portrait study by Shanks was a preliminary idea and to Mould it is apparent why the composition was abandoned for the final portrait.

"It gives so much more than your average royal image ever could," he explained. "On one level you have the Princess Diana that you recognize and see that glamour which turned heads wherever she went."

"At the same time," he said, "you also get her inner world. The feeling of pathos. An indication of the turmoil through which she was going at this stage."

Following Charles and Diana's official separation in 1992, the press intrusion faced by the princess increased dramatically with speculation about her friendships and behavior regularly making the front pages of world tabloids.

The year the portrait was painted, 1994, was also the year that Charles took part in an interview with journalist David Dimbleby in which he spoke about the breakdown of his marriage and admitted that he had been unfaithful to Diana after their union had "irretrievably broken down."

On the evening of the interview's broadcast, Diana made a showstopping appearance at a charity event wearing a short black cocktail dress by the designer Christina Stambolian. The dress was an instant hit and images of the glamorous royal made the front pages the next morning drawing some attention away from the prince's interview. The Stambolian design has since been labeled the "revenge dress."

In the Shanks portrait, Diana is wearing a green velvet halter neck tuxedo dress by her most trusted designer, Catherine Walker. Though the royal never wore it for a public appearance, the dress was immortalized in a sitting with Mario Testino in 1997 ahead of the auction of her most memorable gowns at Christie's which raised $3.2 million for charity.

The portrait will be displayed by Philip Mould & Co. at the Masterpiece Art Fair until July 6.

Join half a million readers enjoying Newsweek's free newsletters