The British It girl, who was found dead in her London apartment last Wednesday, was found to have died of a perforated ulcer, a year after revealing she had been diagnosed with a non-malignant brain tumour and autoimmune condition.

Palmer-Tomkinson's sister, Santa Montefiore, shared the news on Twitter.

"Today the coroner's report states that Tara died of natural causes – a perforated ulcer," Montefiore wrote. "She did not have a brain tumour."

The author continued by clarifying that her sister was, contrary to previous reports, not the goddaughter of Prince Charles.

She added that the socialite had been in "high spirits" in the days before her death.

"She had plans, trips [and] had written a moving new song," she wrote.

In a statement released by the family shortly after the tweets were sent, it was revealed that Palmer-Tomkinson, who was known for her battle with drug addiction, had not displayed depressive tendencies prior to her death.

"Those that knew and were close to Tara knew that there was no retreat to a 'dark place' as some have disappointingly sought to suggest. In the last few weeks Tara was happy, positive and making plans for when she recovered her health," the statement read.

"As usual she had been busy with the friends and family she loved, and who loved her in return."

The statement revealed Palmer-Tomkinson will be farewelled at a private service on February 27.

The daughter of British Olympic skier Charles Palmer-Tomkinson, Tara Palmer-Tomkinson was born into a wealthy family who were friendly with the royals.

In the 1990s, the socialite had a weekly column for the Sunday Times, which was later revealed to have been ghostwritten. Her 2007 book, The Naughty Girl's Guide to Life, was similarly co-authored.

Although she dabbled in music and reality television appearances, Palmer-Tomkinson was best known for her cocaine addiction.

She appeared while under the influence in a 1999 appearance on ITV talk show program The Frank Skinner Show, forgetting the host's name.

In 2006, she made headlines when her nasal septum collapsed. She later underwent plastic surgery to have it reconstructed.

In 2014, she was arrested at Heathrow Airport for bad behaviour following the refusal of a staff member to let her into a first-class lounge.

Last November, the socialite revealed she had a benign tumour in her pituitary gland. Her treatment for the tumour was reported to have been successful.

Fairfax Media