David Cameron will meet US presidential candidate Mitt Romney at Downing Street today, during Romney's visit to the capital.
The Republican candidate is using the trip to raise campaign funds and canvass for support among London's large American community.
Romney, who is trailing Democrat president Barack Obama by a narrow margin in the latest polls, is also due to meet Deputy Prime Minister Nick Clegg and Labour Leader Ed Miliband.
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Kurt Cochran and his wife Melissa had been visiting London from the US to celebrate their 25th wedding anniversary and were due to fly home.
The Government has previously described the new coin - which enters circulation tomorrow - as "harder to counterfeit than ever before".
The European bloc said that Russia should release hundreds of people it arrested at anti-government protests and rallies.