The sign, which reads “Bed Peace”, sold yesterday at Christie’s auction house in South Kensington, London. It was bought by an anonymous telephone bidder for £97,250.
The placard was made by Lennon when he held his week-long bed-in in Montreal, Canada, in 1969 in protest at the Vietnam War.
The couple had held a similar event during their honeymoon in Amsterdam – an event immortalised in the Beatles song The Ballad of John and Yoko.