Image caption Scores of letters written by John Lennon have been sold at auction over the years

More than 250 letters and cards sent by John Lennon to his family and friends are to be published for the first time.

Author Hunter Davies, who wrote the only official biography of The Beatles in the 1960s, is trying to track down every missive written by the singer.

"I've found a lot of letters that nobody's ever seen," he said.

Davies, whose book comes out next year, said it was the first time Lennon's widow Yoko Ono had given permission for his private letters to be published.

The author said there were "no dramatic revelations" but that the letters gave an insight into Lennon's life and his humour.

"You see him as a tortured soul," he said. "You see him being funny, you see him showing off, you see him depressed, you see him in different stages."

Davies has tracked down some correspondence through auction houses that have sold Lennon memorabilia over the years.

Relatives, members of the Beatles inner circle, memorabilia dealers and collectors have also given access to letters.

"His first reaction to any emotion, whether it was fury or amazement or hatred, was not really to go to the piano or the guitar," the author said of Lennon.

"He was just as likely to pick up a pen and write it. And he wrote such amusing letters.

Image caption A letter to Lennon's first wife Cynthia was auctioned at Christie's in 2006

"When he wrote a letter or a postcard to somebody, he saw it as a challenge to write a unique piece for them and to amuse them and respond to their humour."

Mr Davies was speaking at the annual Beatles Convention in Liverpool, part of International Beatle Week, which drew fans from around the world for tribute bands, talks, tours and a memorabilia fair.

The speakers also included Lennon's half-sister Julia Baird, who wrote the story of their family in her memoir Imagine This: Growing Up With My Brother John Lennon.

She said she had to set the record straight after being confronted by inaccuracies in accounts by Beatles experts.

"When I die I will know that I didn't let my mother's name be sullied and do nothing about it," she told the BBC.

"I was exasperated for a long, long time, and then I thought, you've got to do something with that energy. So I decided to write."

The event also saw John Lennon's original band return to the high school where they founded the group that would become The Beatles.

On Saturday, The Quarrymen performed in the school hall at Quarry Bank School, now called Calderstones School, where they played with Lennon as teenagers in the 1950s.

Banjo player Rod Davis - who was replaced by Paul McCartney in the band - said: "It was great fun.

"The school hall looks even better than I remember it 50-odd years ago. We actually played on that stage for a couple of school dances. So it was pretty authentic really."