Britain’s Prince Harry greets Brazilian model Fernanda Motta during an award ceremony after playing a charity polo match in Campinas, Brazil.

LONDON (AP) — Say goodbye to the party prince; say hello to the queen’s secret weapon.

That’s how royal watchers have seen Prince Harry’s first major diplomatic tour — a 10-day jaunt to the Caribbean and South America to represent his grandmother Queen Elizabeth II as part of celebrations marking her Diamond Jubilee.

The trip offered Harry, 27, a first step onto the international stage in a role that will become increasingly common as a younger generation of royals step to the fore.

The official part of the trip, which also included a business-boosting visit to Brazil, ended Sunday with a charity polo match after which Harry gave an exuberant thumbs up after he was kissed on the cheek by a brunette model. On Monday, he set out for Brazil’s interior to study its ecosystems as part of a private project conducted by the charitable foundation he runs with his brother, Prince William.

Press reports emphasized that Harry had been a hit with locals and made good on his vow to make his grandmother proud.

Robert Lacey, author of several books about the queen, said Harry’s successful trip reflects his new maturity.

“He’s grown into this role in the last few years, in part because of his military career,” Lacey said “There were concerns because of some mishaps over the years that Harry would be the troublesome one in the family, but he’s really doing remarkably well.”

As a younger man and teenager, Harry raised eyebrows with his fondness for partying and — most notoriously — when he wore Nazi gear to a costume party and was photographed wearing a swastika armband.

Lacey said Harry’s British military training, and that of his elder brother, Prince William, has greatly impressed the public.