The Prince and Princess of Wales, who rarely show public displays of affection, couldn't resist cosying up to each other after Kate let her hair down at the royal residence.
William was seen placing his hand on his wife's lower back and Kate reciprocated the sweet gesture by placing her hand on her husband's back before holding his hand.
Prince William was spotted putting a reassuring arm around Kate during a reception at Buckingham Palace
Kate, who earlier in the day wore her hair up in a sleek bun under a hat by Jane Taylor, let down her brunette locks and they fell in loose curls down her shoulders as she cut a more relaxed figure.
The princess looked chic in a £3,000 caped red coat from Catherine Walker and Gianvito Rossi shoes.
To add a further glamour to the look, Kate sported a pair of Princess Diana's sapphire and diamond oval drop earrings.
The royal has worn a similar coat dress on many occasions, including during her Christmas Carol concert at Westminster Abbey in 2021. She wore a black version of the same dress to Prince Philip's funeral.
The shoes are also a firm favourite of Kate's - with her owning the heels in at least six colours.
Earlier in the day Kate and William travelled with Mr Yoon and Mrs Kim to a Horse Guards Parade ceremonial welcome, where the King and Queen were waiting.
Charles and Camilla took their place standing on the royal pavilion around midday and briefly greeted Prime Minister Rishi Sunak, Foreign Secretary Lord David Cameron, Home Secretary James Cleverly and the Defence Chiefs of Staff.
Camilla wore a blue dress and coat by Anna Valentine, hat with loose feathers by Philip Treacy and a sapphire and diamond brooch which belonged to Queen Mary.
The Prince and Princess of Wales, who rarely show public displays of affection taking example from Queen Elizabeth who did not hold hands with her husband Prince Philip in public, couldn't resist cosying up on Tuesday
As the pair appeared loved up during the lavish reception to welcome president Yoon Suk Yeol and First Lady Kim Keon Hee of South Korea in London
William was seen placing his hand on his wife's lower back and Kate reciprocated the sweet gesture by placing her hand on her husbands back before holding his hand
Nearby was the Sovereign's Escort of the Household Cavalry Mounted Regiment, the Life Guards and the Blues and Royals, commanded by Major Edward van der Lande.
A guard of honour, formed by F Company Scots Guards, gave a royal salute amid traditional pomp and pageantry - and the King and Mr Yoon inspected the troops.
Members of the Scots Guards were recently deployed to South Korea where they were training troops. Mr Yoon walked past the two ranks of Guardsman casting his eye over the servicemen before returning to the royal pavilion with the King.
The VIP visitors were greeted by Their Majesties as the national anthem of Korea was played and a volley of ceremonial salutes could be heard ringing out across the capital.
Major James Drummond Moray matched forwards and presented his Guard of Honour to the Korean President and invited both himself and the King to inspect it.
Kate was all smiles as she sported an all-red ensemble for the ceremonial welcome for President of South Korea
The Prince and Princess of Wales met with Yoon Suk Yeol, South Korean President, and his wife Kim Keon Hee
The British royals took a photo together with Yoon Suk Yeol and his wife, on day on the state visit
The royals and their guests then departed in a procession of carriages. The King and President riding in The Irish State Coach, while
The Australian State Coach contained the Queen and First Lady.
The Prince and Princess of Wales rode in The Scottish State Coach with His Excellency Choo Kyungho, Deputy Prime Minister and Minister of Economy and Finance.
Other senior officials followed in a string of Semi-State Landaus.
At Buckingham Palace a Guard of Honour, found by 1st Battalion Welsh Guards, with the King’s Colour, under the command of Major Andrew Campbell, Welsh Guards, with the Band of the Regiment, took position in the Quadrangle to greet the carriages, as well as a dismounted Detachment of Household Cavalry in the Grand Entrance.
Will and Kate were in the carriage together as they took part in a welcome ceremony
Kate opted for a glamorous make-up look for the day out
Princess of Wales and Prince William, Prince of Wales return to Buckingham Palace
Queen Camilla and the wife of the President of South Korea Kim Keon Hee travel by carriage from Horse Guards to Buckingham Palace
Charles grinned from his state carriage following the ceremonial welcome today
As the parties arrived the Guard of Honour received Their Majesties, Their Excellencies and Their Royal Highnesses with a Royal Salute, while the band played the Korean and British National Anthems.
170 guests will gather for the banquet, customarily a white tie and tiara affair, in the opulent Palace ballroom.
The King and Queen are expected to be joined other members of the royal family, while Charles and Mr Yoon will make speeches.
Foreign secretaries are also usually invited, meaning the newly appointed Lord Cameron of Chipping Norton is likely to make a return to dining at the royal residence, harking back to the days when he was prime minister.
Mr Yoon, 62, is a known fan of karaoke and in April belted out a verse of one of his favourite songs, American Pie, at a White House dinner at the request of President Joe Biden during a state visit to the US.
Mr Yoon and Mrs Kim made a low-key arrival at Stansted Airport on Monday