PM set for Late Show With Letterman

David Cameron is to appear on one of the US's most influential TV shows to "bang the drum for Britain" and encourage Americans to visit or set up a business here, Downing Street has revealed.

The Prime Minister is flying to New York to attend the United Nations General Assembly where he will deliver a keynote speech on Wednesday. Before the speech he will issue a challenge to world leaders to live up to their promises on aid for developing countries.

But along with his packed schedule of diplomatic work and meetings with fellow leaders, he will go into the studio to record an interview for the Late Show With David Letterman.

Letterman has been a fixture on late-night TV in the US for 30 years, and his mixture of heavyweight interviews and humour including his famous Top Ten lists draws a daily audience of three million or more and frequently creates news headlines with big-name political guests.

Barack Obama has appeared on Letterman seven times, twice since becoming president, most recently using the CBS show last week to deliver a slapdown to election rival Mitt Romney for his comment that 47% of US voters see themselves as "victims".

Mr Cameron will hope to use his appearance on Wednesday to build on the high profile won for Britain by the London Olympics and Paralympics this summer.

Shortly after his arrival in New York, Mr Cameron will call on leaders of rich countries to honour their promises to achieve the UN's eight Millennium Development Goals (MDG) for the developing world, which include eradicating extreme poverty, getting all primary-age children into school, cutting child mortality and improving maternal health.

With less than three years to go to the 2015 deadline, fewer than half of the 142 MDG objectives are on track for delivery, the PM will warn.

He will tell wealthy states that the economic downturn should not be used as an excuse for failing to fulfil their pledges.

"The first thing we must do is send a clear message to everyone who signed up to Millennium Development Goals - that now is the time to step up and honour those promises. And I know there are some who say we can't afford to do that right now. They believe we have to focus on ourselves. And if that means breaking promises, then they're sorry but it just has to be done. Well I'm sorry, but it doesn't," Mr Cameron is expected to say.