Nelson Mandela memorial: New Zealand PM John Key is the 'unidentified guest'

John Key, or - as he is also known - "unidentified guest" (Getty Images)

Another day, another unedifying detail to help make the Nelson Mandela memorial service bigger on the world-leader-embarrassment scale than the Wikileaks diplomatic cables.

After the crowds booed South African President Jacob Zuma, and a photographer caught the assorted leaders of the UK, US and Denmark posing for a selfie like Glastonbury drunkards, New Zealand's Prime Minister has been labelled an "unidentified guest" in the event's photos.

There he was, leader of a country half the size of London, hobnobbing with the world's great and good. But after the event the people of New Zealand were dismayed to see the European Pressphoto Agency's caption on a picture of "British Prime Minister David Cameron laugh(ing) with an unidentified guest ..."

The "unidentified guest" was Mr Key.

The popular PM, a former high-flyer in investment banking, is no stranger to mild awkwardness. In 2010, during a press conference about changes in early years school funding, he was asked what he'd do if his wife had another child, who had to go through his new system. He answered: "I'd be extremely worried, because I've had a vasectomy."

Faced with a deathly silence in the room, Key admitted that was "probably too much information."

"Boy that's slowed things down," he said. "Any other questions?"

And in 2011, Key was jubilant when President Barack Obama agreed to meet him in the Oval Office. At the subsequent press conference, however, Obama repeatedly referred to him as "Prime Minister Keyes." Perhaps the worst part, said the Press Association, was that nobody seemed to notice.

Kiwis are used to bruises of national confidence, what with being a tiny country miles from pretty much everything. But, being home to the Lord of the Rings films, Flight of the Conchords and perhaps the greatest sporting team in human history (the All Blacks), they'll probably get over it.

Video: 'Fake' Mandela interpreter defends himself