
The candid snap, posted to Instagram yesterday by Valentino co-founder Giancarlo Giammetti, shows the late royal with wet hair holding a drink, in a colourful print bikini with a purple shirt tied at her waist.
By the time it was taken, the princess and her husband had effectively been living separate lives for around four years with Prince Charles resuming his relationship with his former girlfriend Camilla Parker-Bowles in 1987.
Meanwhile, the Princess had been engaging in a two-year affair with Household Cavalry officer James Hewitt, who she would later famously tell the world she ‘adored’, as well as a relationship with her bodyguard Barry Mannakee whose death in 1987 she described as ‘the biggest blow of my life’.

But unearthed photos of Princess Diana on board a yacht in Italy with Kyril, Prince of Preslav, and the designer Valentino taken in 1990, two years before her separation from Prince Charles, show the late royal looking pensive and unsure.
Giancarlo, who co-founded the fashion house with Valentino Garavani, also shared another photo of the two of them greeting the princess at a formal event. It’s not known when it was taken.