The late former US president Jimmy Carter was a relative novice at international diplomacy when made his first visit to the UK just four months into his term in the White House in 1977 – which resulted in him earning the displeasure of the Queen Mother after being said to have given her a parting kiss on the lips.

It was the year of Queen Elizabeth’s Silver Jubilee, marking her 25th year on the throne,

and world leaders attending a G7 summit were invited for a state banquet in Buckingham Palace where they were to meet the Queen and other members of the Royal Family.

Photographs showed Mr Carter and the Queen Mother being all smiles as the president escorted her by her white-gloved hand to their places in a formal group portrait with the G7 leaders before dinner.

But the evening would end with a short moment which would spark debate among British tabloids and the American media for decades afterwards, with the president accused of a total ignorance of royal protocol.

As they said goodbye, the US president is said to have kissed the royal on the lips. The story emerged six years later in a newspaper column, which revealed the Queen Mother had given an “anti-toast” to people who she does “not particularly like”, according to an unnamed dinner guest at her London residence of Clarence House.

“Tony Benn, Idi Amin, Jimmy Carter,” were on the Queen Mother’s list for this occasion, placing Carter in line with a prominent anti-royalist and Uganda’s former military dictator.

When she was questioned on the inclusion of the president by a guest, the Queen Mother said: “Because he is the only man, since my dear husband died, to have had the effrontery to kiss me on the lips,”.

In her official biography published in 2009, William Shawcross recounted a conversation where the Queen Mother said she “took a sharp step backwards” when she saw Mr Carter leaning in – but it was “not quite far enough”.

While Mr Carter would not have been required to bow in front of the royals – a handshake would have been accepted – such overfamiliarity is a severe breach of usual protocol.

Mr Carter denied the Queen Mother’s account of events, writing in a 2015 autobiography that he “kissed her lightly on the cheek” before she thanked him for visiting.

“More than two years later, there were reports in the British papers that grossly distorted this event, stating that I had deeply embarrassed her with excessive familiarity. I was distressed by these reports but couldn’t change what had happened — nor did I regret it,” he added.

Mr Carter was remembered fondly by many in the UK following his visit, and in 2022, following the death of the Queen, he said her “dignity, graciousness, and sense of duty have been an inspiration, and we join the millions around the world in mourning a remarkable leader”.