Unseen footage of The Beatles' American tour in 1964 will be is up for auction with a guide price of £4000-£6000.
It was filmed by a 15 year-old fan at an unscheduled gig in Kansas City, and afterwards lay forgotten in a drawer at his parents' home for decades.
He explained: "We cleared out my parent's estate two months ago.
"And there I discovered it at the bottom of the old drawer, still lying in its original photo-lab box with 'Beatles 1964' on the back where I'd feverishly scrawled it in blue ballpoint pen - the one and only motion picture of the one and only concert the Beatles would ever perform in Kansas City."
The concert was put on at the last minute when the Kansas City municipal stadium offered a record-breaking 150,000 dollars to Beatles manager Brian Epstein to add the date to their tour.
The 8mm silent colour film reel is approximately two minutes long, dating from September 17 1964, and will be auctioned by Berkshire firm Cameo on November 4.