Some of his songs were banned after being deemed too risqué
A collection of George Formby's banjoleles, including the one he used to record When I'm Cleaning Windows, are to go up for auction.
The Abbott Monarch banjolele, which the Wigan film star referred to as "Little Strad", is believed to have been his favourite instrument, Bonhams said.
It is expected to fetch about £45,000 when it goes under the hammer in June.
Also in the sale is Formby's gold-plated banjolele which was used during his live performances.
The instrument was presented to the star in 1930 by Dallas, the instrument maker.
It was later owned by Beatle George Harrison.
Harrison met George's nephew Jeffrey Formby at a concert in Digswell, Welwyn Garden City.
Harrison offered to return the instrument to the family as a gift although Jeffrey preferred to purchase it, Bonhams said.
A copy of a letter from George Harrison to Jeffrey, dated 1991, is included with the lot.
The gold-plated banjolele is estimated at £20,000 to £35,000.
George Formby's Dallas C banjolele will also be sold - with a guide price of between £20,000 and £30,000.
A banjolele has the body of a banjo but a neck like a ukulele.
Formby was born George Hoy Booth in 1904, in Wigan, Lancashire, the son of a successful music hall comedian.
George's early career was as a jockey but, following his father's death in 1921, he became a music hall performer himself, drawing on his father's material.
He took up playing the ukulele as a hobby but, after incorporating it into his act, it became his trademark.
His cheeky, happy, but accident-prone persona endeared him to audiences and his musical style established him as a superstar of his day.
His songs contained lyrics often laden with double entendre and these were accompanied by his highly individual, syncopated style of banjolele playing.
Some of his songs were deemed too risqué for broadcast and the 1937 composition, With My Little Stick Of Blackpool Rock, was banned by the BBC.
His other famous songs include Leaning On A Lamppost and Chinese Laundry Blues.
Bonhams Entertainment sale takes place in Knightsbridge, London, on 18 June.