Neil Armstrong missed out an "a" and did not say "one small step for a man" when he set foot on the Moon in 1969, a linguistic analysis has confirmed.

The researchers show for the first time that he intended to say "a man" and that the "a" may have been lost because he was under pressure.

They say that although the phrase was not strictly correct, it was poetic.

There is also new evidence that his inspirational first words were spoken completely spontaneously - rather than being pre-scripted for him by Nasa or by the White House.

In 2006, an analysis by an Australian entrepreneur added credence to these explanations - as it found there was a gap for the "a". However, subsequent analyses disputed this conclusion.

To settle the argument, Dr Chris Riley, author of the new Haynes book Apollo 11, An Owner's Manual, and forensic linguist John Olsson carried out the most detailed analysis yet of Neil Armstrong's speech patterns.