MONTREAL—At one point during John Lennon and Yoko Ono's bed-in for peace in Montreal 40 years ago, he scrawled the words “l’amour et la paix” (love and peace) in block letters with a felt marker on a white placard, then stuck it to a wall with tape. Now the placard is estimated to be worth $70,000, and it will be auctioned July 1 at Christie’s London.

The auction house says the placard has "rare, irrefutable provenance" and is selling it along with an Ivor Sharp photo of the couple with the sign behind them, as well as a print of a drawing of Lennon placing a ring on Ono's finger. The bed-in took place in Room 1742 of the Queen Elizabeth Hotel, where the newly married couple stayed for seven days to promote their antiwar message. The former Beatle and assorted visitors recorded "Give Peace a Chance" there, and the event's 40th anniversary is being marked at the Montreal Museum of Fine Arts, where photos and artifacts are on display.

Read more at the Toronto Star.