The UK Prime Minister gave a speech in which she spoke of the leaders being “close friends” with a “unique understanding of each other”.
She even hailed the “memorable occasion” of the biannual summit.
But it appeared the Australian leader was more interested in the contents of his phone than the “unique” friendship between the countries.
Throughout Mrs May’s speech he was filmed tapping away on his mobile, seemingly not listening to the Prime Minister’s call for unity.
The Commonwealth Heads of Government were at Windsor Castle for the retreat where they discussed whether Prince Charles should succeeding his mother the Queen as head of the 53-nation alliance.
During her address, Mrs May said: “At the very moment that international co-operation is so important, some nations are choosing instead to shun the rules-based system that underpins global security.
“I’m sure today will be a memorable event and by the end of which, I’m sure we’ll be able to leave even closer friends and with a unique understanding of each other in ways which cannot be matched by other summits.”
During the meeting the world leaders agreed that the Prince of Wales should become the next leader – a role that is not necessarily hereditary.
The decision, which had already been backed by the British government, came after the Queen made a personal appeal to choose her son for the role.
During the opening of the Commonwealth Heads of Government Meeting she told them it was her "sincere wish" that the family of nations would one day decide the prince should carry on the Commonwealth work started by her father King George VI.