He'd already questioned the preparedness of Britain to host the Olympic Games and today Mitt Romney added to the gaffe-count of his UK visit by appearing to forget Ed Miliband's name during a press conference.

Speculation on the social networking site Twitter was centered on whether Mr Romney had forgotten the Labour leader's name - or didn't in fact know it in the first place.

At a press conference the possible-future-president of the United States referred to Ed Miliband as 'Mr Leader'.

Romney said: "Like you, Mr Leader, I look forward to our conversations this morning ... and recognise, of course, the unique relationship that exists between our nations, our commitment to common values, our commitment to peace in the world and our desire to see a stronger and growing economy."

Mr Romney had already been perilously close to offending his British hosts by questioning the preparedness of London for the Olympics.

Speaking to NBC news ahead of today's meetings Romney said, “It's hard to know just how well it will turn out.

“There are a few things that were disconcerting.

“The stories about the private security firm not having enough people, the supposed strike of the immigration and customs officials - that obviously is not something which is encouraging.”

He also questioned the British enthusiasm for the Olympics, asking: "Do they come together and celebrate the Olympic moment? And that's something which we only find out once the Games actually begin." he said.

British Prime Minister, David Cameron, was later prompted to respond to Romney's comments saying: "We are holding an Olympic Games in one of the busiest, most active, bustling cities anywhere in the world. Of course it's easier if you hold an Olympic Games in the middle of nowhere."

This appeared to be a reference to Utah, which was the site of the games that Romney managed.

Cameron, however, stopped short of criticising his US guest, telling reporters: "I think we'll show the whole world not just that we've come together as a United Kingdom, but also we're extremely good at welcoming people from across the world."

During the meeting with the Prime Minister, Mr Romney appeared to be backtracking on his earlier comments, saying of the security issues and the error over the North Korean team flag: "It is impossible for absolutely no mistakes to occur," he said.

"Of course there will be errors from time to time, but those are all overshadowed by the extraordinary demonstrations of courage, character and determination by the athletes."

“The Games are, after all, about the athletes, the volunteers and the people of the community who come together to celebrate those athletes.

“As soon as the Games begin, we all forget the organisers and focus on the athletes.”

Romney's visit to London also took in talks with George Osborne, Deputy Prime Minister Nick Clegg, Labour leader Ed Miliband, former PM Tony Blair and MI6 chief Sir John Sawers.