Prince Harry has been keeping in touch with his older brother Prince William throughout his Diamond Jubilee tour, seeking the Duke of Cambridge's advice.
The brothers have been texting and calling during Harry's his first solo trip, with William giving the younger prince advice on "how to mix the informality with the dignity of (representing) the Queen", according to a source.
The source said: "He spoke at length with his brother before coming out about how to approached it, and they have been in communication throughout the tour.
"They have been in touch regularly via mobile and text. The relationship they have is full of banter and humour, but Prince William is deeply caring of his younger brother and wants his younger brother to succeed."
Harry's trip on behalf of the Queen, which ends today, has been seen as many as a success and brought the royal new admirers during his travels to Belize, the Bahamas and Jamaica, including Miss Bahamas and Usain Bolt.
Pictures of Harry posing with the fastest man in world were splashed over many front pages, as the prince struck a memorable pose with the Olympic runner.
In Belize Harry enjoyed a Diamond Jubilee street party with the locals, who had him dancing with performers, tasting local food and even downing shots of rum.
The Bahamas gave the prince the chance to join the country in formally honouring the Queen at a national service of thanksgiving.
Harry also charmed Jamaica's staunchly republican prime minister Portia Simpson Miller who plans to end centuries of constitutional ties with the British monarchy by replacing the Queen as head of state with a Jamaican.
The tour was held to celebrate the monarch's Diamond Jubilee but an offshoot of the visit has been to introduce the third-in-line to the throne to some of the sovereign's realms.
As well as being aware that his brother was watching how he performed, Harry also knows "that the Queen is following the tour as well", the source said.
The prince had specifically asked to tour the Caribbean, though it was the Queen who chose the countries he would visit, and he "mugged up" on the detail of what he would be doing in each country because "he really wanted to do the best for his grandmother and for the three countries", said the source.
"What we have seen of Prince Harry is Prince Harry - he is just himself and he has got natural enthusiasm and energy and is someone whose character lends itself very well to this region.
"He has got a flexible approach to his work and he has got great empathy with people; it's something he innately has, it's not something that can be taught."
At his last official engagement of the tour Harry was invited to enjoy a Jamaica night at the exclusive Sandals Royal Caribbean Resort in the popular holiday area of Montego Bay last night.
During the performance of music, dance and song, he tapped his feet and nodded to the rhythms, and at one point mouthed the words of the Bob Marley hit Three Little Birds as a violinist played the tune.
He was also presented with a blend of 30-year-old Jamaican rum, with another bottle for his brother.
The prince leaves Jamaica later today for a three-day visit to Brazil where he will promote the UK on behalf of the Government when he arrives tomorrow.
When he returns to Britain his military career will be his focus for the rest of the year, with the likelihood the royal Apache pilot will return to Afghanistan soon.
The source said he was keen to carry out more tours on behalf of the Queen, but "what happens in 2013 is a long way off and he is not really thinking about that".