The two copies of 16mm colour cine film had been given to the owner over 40 years ago by her father, a film technician who had worked for the BBC and Visnews, a large London-based international news agency bought by Reuters in the 1990s.
Auctioneers Bainbridges of Ruislip are to offer the reels, which have remained under the vendor's bed in Hayes since, in their September sale and believe them to be distribution copies of the coverage by Visnews.
According to research carried out by the auction house, the production is not listed on the British Film Institute's Visnews archive and cannot be found on YouTube or Google, suggesting that this could be lost footage unseen since 1969.
Both six-minute films capture the build-up to the launch on July 16 at the Kennedy Space Center in Merritt Island, Florida, with colour footage of the command centre, the launchpad, the crowd, the astronauts - including Armstrong, who died last month - and the take-off.
This would not be the first time original recordings of the legendary mission have caused a stir. In 2006, NASA admitted that the SSTV recordings of the actual moon landing were lost but has since released newly restored copies of the original broadcast.
The sale takes place on September 27 where the films have been estimated at £200-300. Footage is to be posted on the auction house's website prior to the sale: www.bainbridgesauctions.co.uk.