Betty Westwood, 58, has entered a treasured piece of memorabilia in a London auction.

Lot no. 301 at Bonhams sale in Knightsbridge on June 18 is a publicity photograph signed by Lennon and includes sketches of a record cover for the album Beatles For Sale.

Bonhams have estimated the sale price at £3,000 to £5,000 but the picture could go for much more.

Betty said: "They are taking bets at my office about how much it will fetch."

Her husband David, 57, sales representative, took the photograph out of its envelope in the loft to get it valued by Bonhams.

He was inspired by the recent sale of a Rolling Stones poster for £7,800. "I thought: 'Crickey!'" he said. "The picture might be worth a lot of money.'

"Betty went to see the Beatles at the Odeon in Leeds in 1964 when she was just 14. Members of the fan club could take pictures along to the stage door for the Beatles to sign after the gig.

"In most cases it was the roadies who signed them – there were just too many for the Beatles to do alone. But when Betty got hers back, she saw John had sketched on the back his ideas for the album cover of their next LP.

"He probably grabbed the nearest piece of paper available and it was Betty's photograph. So outside the music industry Betty was the first person to know what the next album would be called."

Betty remembered: "I was obsessed with the Beatles in those days and I liked John the best because of his character. I always had a thing for him.

"I don't listen to their music as much as I used to although I got a CD as a Christmas present two years ago. I still have scrapbooks and fanzines.

"I always kept the photograph in an envelope in a plastic carrier bag in the loft and thought that one day my kids would throw it away.

"My younger daughter is in New Zealand and we would like to use some of the money to visit her."