George Osborne has revealed the thinking behind the relaxed dress code at the G8 summit, saying an informal atmosphere is more conducive to getting work done.
The chancellor made the comments after being asked why he appeared without a tie yesterday.
"Basically I did what I was told to do, which was turn up in what they call 'smart casual' wear," he said.
"So I followed to the letter, I got out my jacket and my blue shirt.
"The interesting thing about this conference - I've never been to a G8 before, I'm here to present one of the sessions on tax - is that it is informal, despite the enormous fuss that goes with having a conference like this, despite the huge media present.
"Actually, when you get into the hotel, it is quite intimate and informal."
He added: "This is actually an extraordinary opportunity to get things done where, perhaps where things are more formal, and people are in more entrenched positions, that's more difficult."
The comments came after a meeting last night in which only world leaders were present, without their advisers.
Cameron even oversaw the use of a small table, which world leaders crammed around, in a bid to restrict the number of people in the room.
The prime minister also took time out yesterday to post the menu for the dinner the leaders ate.
The summit is winning relatively warm reviews so far, with some aid groups pleased with efforts on tax transparency.
But Syria presents a far more difficult problem. Cameron presented a 'common ground' plan in a bid to construct a final position which all leaders – including Russian president Vladimir Putin – could sign up to.
It is unclear whether that has been successful, although there are relatively positive messages coming out of the Northern Ireland hotel complex.