KEY POINTS:
An audience with the Queen; a meeting with the British Prime Minister and another with the leader of the Conservative Party; breakfast with the Mayor of London; a little time hanging out with the All Blacks and some mingling with a sprinkling of London's celebrities.
Oh, and an emotional meeting with a long-lost half-brother.
It was a remarkable 12 hours for Prime Minister John Key.
The only dampener on his trip to London was the issue of Britain's controversial new air-departure tax - a tax the travel industry has warned threatens New Zealand's billion-dollar British tourist market.
The issue was of particular significance to Mr Key who has, in addition to his prime ministerial duties, taken on the role of Minister of Tourism.
His visit to London largely centred on promoting New Zealand tourism. He made three trips during the day to Tourism New Zealand's giant, 25m-long, inflatable rugby ball, which has been erected at Potters Fields Park, near Tower Bridge.
Therefore the timing of a new tax which increases the cost for British tourists flying to New Zealand and which was announced in Britain's pre-Budget package just hours before Mr Key arrived in the country was problematic. The issue subsequently dominated his meeting with his British counterpart, Gordon Brown.
But Mr Key's camp was quick to point out that state visits are not just about meet-and-greets, but are also about resolving pressing issues. Even though Mr Key would not comment on whether he received reassurance from Mr Brown over the departure tax, the issue was seen as adding some seriousness to the discussions.
But it was his meeting with his half-brother Martyn Key, 68, which provided the touching note. The two brothers had never met before and only got in contact after Herald journalist Eugene Bingham tracked down Martyn Key in an investigation into the life of John Key, published in July.
Mr Key met Martyn Key, his wife, Carole, and their son Milo in a London hotel. The two men later said they discussed their shared father, George, and other personal issues.
"It was a great meeting and a fairytale story to come out of the election." Mr Key said.
Martyn Key joked that he used to look like Mr Key, who is 20 years his junior, when he was younger, and physically leaned to the right, towards his brother, when asked about his own politics.
"He's very charismatic," Martyn Key said. "This is all absolutely surreal. I'm stunned but very proud."
Mr Key finished his visit to London back at the giant rugby ball, where a cocktail reception was held for the ball's London opening.
During his speech to the reception, Mr Key lamented that he would miss the All Blacks' test against England on Saturday - joking that he was the only New Zealand leader to voluntarily leave a city so close to a big match.
But for the new Prime Minister it seems even the prospect of watching an All Black victory at Twickenham could not keep him from returning home as soon possible - since being sworn in last Wednesday Mr Key has spent only one day in the country.
