John Lennon once approached Eric Clapton with a plan to form a supergroup, according to correspondence that will go under the hammer at an upcoming Profiles in History auction next month (Dec12).

A "distinguished American private collector" is selling off his treasure trove of 3,000 letters through the auction house over the next two years and his first 300 items of correspondence will go under the hammer on 18 December (12).

They feature a handwritten letter Lennon wrote to Clapton in September, 1971, suggesting they should form a band.

The late Beatle writes, "Both of us have been thru (sic) the same kind of s**t/pain that I know you've had - and I know we could help each other in that area - but mainly Eric - I know I can bring out something great - in fact greater in you that had been so far evident in your music, I hope to bring out the same kind of greatness in all of us - which I know will happen if/when we get together."

That correspondence is expected to fetch $30,000 (£18,750).

But it won't be the big item at the auction - the highlight is expected to be a handwritten letter Ludwig von Beethoven sent to Tobias Haslinger, a friend and business partner of the composer's publisher, concerning the second performance of the 9th Symphony and the Missa Solemnis.

The note is expected to fetch upwards of $40,000 (£25,000).

Letters written by Cole Porter, Louis Armstrong and Peter Ilyich Tchaikovsky will also be sold to the highest bidder at the upcoming auction.