The footage of Neil Armstrong's "one small step" is considered among the most important artefacts of the 20th century but the original NASA tapes have been mislaid somewhere in the US. It is hoped documentation associated with Mr Clifton's reel will help direct researchers to the warehouse or museum where the missing tapes are stored - if they still exist.

The grainy black-and-white television images broadcast to 600 million viewers on July 20, 1969, were a photocopy of a photocopy of the original images captured on the moon's surface by a specially built camera. Few people ever saw the high-quality original images shot at 10 frames a second and beamed back to the Australian tracking station at the CSIRO Parkes Observatory. When the images reached the tracking station they were transferred onto a one-inch, 60-frame-per-second tape and sent to NASA's Goddard Space Flight Centre, at Maryland near Washington, DC, for safekeeping.

The footage broadcast to the world was shot by a television camera pointed at a monitor receiving the images from the moon. "What was broadcast to the world was nowhere near as good as what was received," said John Sarkissian, an engineer at the Parkes Observatory.

All the Apollo mission flights and moon landings were captured in this way and transferred onto one-inch tapes at Parkes and Honeysuckle Creek in Australia and the Goldstone Observatory in California. The tapes were stored in 2614 boxes containing five reels of tape each and held for years in the US National Archives. By 1984 most boxes were recalled and sorted at the Goddard Centre, but only two of 700 original Apollo 11 tapes have been found. NASA announced last week it was launching a formal search and is recalling all the paperwork associated with the tapes.

In 1979, he ordered the film for $US180 from the Smithsonian Institution in Washington, DC, for use in The Dark Side Of The Moon. Mr Clifton said: "On a visit to Washington I went to [the] Smithsonian and asked if they had any shots of rocket ships travelling. They said, 'Well, we can give you highlights of the moon shot.'

"A week later a delivery came to my film studio in Los Angeles with the can of film. When I opened it up I was gobsmacked because instead of getting a couple of minutes I got nearly half an hour of a complete film. "So I took a couple of shots out of it and cut it together with the Dark Side Of The Moon demo for the Floyd film. But I was so busy I never got a chance to finish it and the film just went into the vaults. "I didn't think another thing about it until a few nights ago when I was watching television and it came on the news. And I thought, 'I have got that stuff.' "

Mr Clifton's business partner and catalogue manager Drew Thompson said their 16-millimetre film version of the Apollo 11 landing contains images never released to the public.