The Duchess of Cambridge wore what she had assumed was a traditional national dress to an event celebrating Solomon Islands’ culture…only to later discover that the dress was actually from the Cook Islands, some 3,000 miles away.

Kate and William were meant to have dressed as Solomon Islanders to the party in the capital of Honiara on 16 September, part of their Diamond Jubilee tour of the Far East and South Pacific.

The sartorial agreement between the government of the Solomons and Clarence House was that the Duke and Duchess would attend the event wearing, respectively, a traditional handmade shirt and traditional dress.

But the gaffe occurred thanks to a woman named Kethie Sunders, an over-enthusiastic member of the Solomon Islands’ welcoming committee, who laid out the wrong clothes in the young royals’ suite.

Kate wore a Cook Islands traditional dress to an event celebrating Solomon Islands’ culture

Kethie Sunders nipped in to the bedroom before the Duke and Duchess arrived, excitedly adding some more gifts of clothing to the ones already laid out inside.

But when the royals arrived, their entourage noticed that the clothes in the suite – a bright blue patterened shirt for William and an elaborate strapless fuchsia dress for Kate – did not match the descriptions of the ones that had been agreed on.

A spokesman for Clarence House said: “We saw they weren’t the same design of the traditional clothes we were told would be gifted.

“So we checked with the Solomon Islands government to ensure the right ones were worn.

“We were reassured the clothes were correct, and so the Duke and Duchess wore them to the event.

“It was not learned until later in the evening that the clothes weren’t from the islands.

“But it was understood that the Duke and Duchess intended to wear traditional Solomon Island clothes and this was appreciated. No offence was caused.”

An official from Government House of the Solomon Islands said: “We are incredibly frustrated that this situation has come about and see Kethie as entirely to blame.

“It was completely inappropriate for her to go to Their Royal Highnesses’ room, which she filled with various things, causing confusion.”

Kate did not manage to wear the actual Solomon Islands dress during the tour, since her outfits had already been planned out for the whole trip, but she did return to England with both dresses.

Her spokesman said: “She still has both dresses, they were a gift, and she also has lovely memories of her wonderful time in the Solomon Islands.”