Princess Diana looks radiant on board a yacht with Prince Kyril of Preslav in unseen photos

Princess Diana looks radiant on board a yacht in Italy with Kyril, Prince of Preslav in never-before-seen photos shared by Valentino co-founder Giancarlo Giammetti.

The candid snap, posted to Instagram yesterday, shows the late royal with wet hair holding a drink, looking tanned and relaxed in a colourful print bikini with a purple shirt tied at her waist.

Believed to have been taken aboard the fashion house’s private T.M.Blue One yacht in September 1990, two years before her separation from Prince Charles, the princess is sandwiched between Prince Kyril, also known as Kyril of Saxe-Coburg, and the Italian designer in the photograph.

She completed her cool look with a pair of large black sunglasses and wore dainty gold jewellery including a chain bracelet and hoop earrings.

Princess Diana looks radiant on board a yacht in Italy with Prince Kyril of Preslav in never-before-seen photos shared by Valentino co-founder Giancarlo Giammetti

In the background is Stromboli, a small island in the Tyrrhenian Sea off the north coast of Sicily containing Mount Stromboli, one of the three active volcanoes in Italy. 

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.

Diana, wearing a chic white blazer with puff sleeves and a turquoise trim with a matching skirt and clutch, grinned as she engaged with the two men. 

Giancarlo captioned the images: ‘And here two moments of friendship with her #princess Diana.’

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 or where it was taken

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 or where it was taken

In September he shared another image of the late princess on board the yacht, believed to have been taken on the same trip.

This one also featured Prince Kyril’s then wife, Rosario Saxe-Coburg – a former model and muse for the fashion designer Valentino.

Kyril, the second son of Simeon Saxe-Coburg-Gotha, Prime Minister of Bulgaria from 2001 to 2005, and Margarita Saxe-Coburg-Gotha, married María del Rosario Nadal y Fuster de Puigdorfila, who goes by Rosario Nadal, in September 1989.

The couple had three children together – Princess Mafalda-Cecilia, Princess Olimpia and Prince Tassilo – but are believed to have separated in October 2009.

In September Giancarlo shared another image of the late princess on board the yacht, believed to have been taken on the same trip, alongside Prince Kyril and Rosario (left)

In September Giancarlo shared another image of the late princess on board the yacht, believed to have been taken on the same trip, alongside Prince Kyril and Rosario (left)

Giancarlo previously shared another image from the trip in July 2014 - showing Diana chatting to Rosario (left) and a young boy (right)

Giancarlo previously shared another image from the trip in July 2014 – showing Diana chatting to Rosario (left) and a young boy (right)

Since 2017 Kyril, now 56, has been in a relationship with British businesswoman and art historian Katharine Butler, 53. He is the godfather of Prince Aristidis-Stavros of Greece and Denmark, son of Pavlos, Crown Prince of Greece.

Giancarlo previously shared another image from the trip with Diana in 1990 in July 2014 – showing the princess chatting to Rosario and a young boy.

Diana was a known yachting enthusiast, reportedly because it was one of the few places she felt able to unwind in private. 

She enjoyed her final holiday with Dodi Fayed on a boat named ‘Cujo’ in July 1997, just weeks before their deaths in a Paris car crash on August 31 the same year. 

Diana was famously photographed kissing Dodi on the vessel’s deck and sunbathing on his father’s yacht’s diving board that same summer.

The boat was used by Dodi as the venue for lavish parties in the South of France, mainly in St Tropez.

Earlier this year the yacht was sold for £171,000, with some observers telling the Sunday Express that the bid was surprisingly low, sparking fears that the memory of Diana was ‘fading’.