LONDON - Somewhere, an aging drummer (identity unknown) is probably still kicking himself.

A newly discovered letter found folded in a book at a Liverpool yard sale has shed new light on the Beatles' early days, revealing that Paul McCartney offered an audition to a mystery drummer in 1960, just a few days before the band left for a formative two-month gig in Hamburg, Germany.

The letter, to be auctioned next month by Christie's, has surprised Beatles scholars. It was written two years before the band bounced drummer Pete Best in favor of Ringo Starr, who arrived just in time to help the Beatles' conquer first England and then the world, earning untold millions along the way.

The Aug. 12, 1960, letter handwritten by McCartney offers an audition to someone who had advertised their availability in the Liverpool Echo newspaper four days earlier. The unsigned ad said simply: "Drummer_Young_Free."

McCartney, who was then playing guitar in the band while the late Stuart Sutcliffe handled bass guitar, offered the drummer an audition with the caveat that if he joins the band he must be ready to travel almost immediately to Hamburg. The Beatles honed their musical chops playing at low-rent clubs in the German city's famed red-light district.

"Expenses paid 18 pounds per week (approx) for two months," McCartney writes. "If interested ring Jacaranda club."

The letter is signed, "Yours sincerely, Paul McCartney of the BEATLES."

It is not known if the drummer came for an audition, and failed to impress McCartney and the others, or if he simply didn't follow up. McCartney addressed the letter "Dear Sir," assuming the drummer was a young man, as there were very few female drummers on the Liverpool rock scene at the time.

Bruce Spizer, author of "Beatles For Sale" and other books about the band, said the Beatles were desperately looking for a drummer to take to Hamburg and eventually chose Best, in part because Best "had a drum kit" and because his mother ran a nightclub where the group had played.

"This shows that Pete wasn't the only person they were interested in," Spizer said. "They needed a drummer and Pete was convenient. It makes sense that they would have responded to some drummer in Liverpool looking for work. My speculation is that two months in Hamburg intimidated him, maybe he didn't want to go and never replied. If he had responded, and if he was good, it might have changed everything."

Christie's spokeswoman Leonie Pitts said the auction house's Beatles experts are certain that the letter was not an early feeler to Starr, who was a successful drummer with a rival Liverpool band, Rory Storm and the Hurricanes, before he joined the Beatles.

She said auctioneers had not contacted McCartney to ask if he knew anything about the drummer who had placed the ad.

Christie's auction house said Monday the letter would likely draw more than 7,000 pounds ($11,000) when it is sold Nov. 15 along with other pop memorabilia.