His brother Mike, 78, told us how the siblings tried and failed to help their father Jim finish it as boys. “I was useless at crosswords,” he laughed. “Our kid was a bit better but dad was the expert.”

Mike was speaking at the former McCartney home, 20 Forthlin Road, Liverpool, as the National Trust – who now own it – prepares to open its doors to aspiring musicians.

The Trust is giving hopefuls the chance to write and perform in the spot where Paul and John Lennon sang the earliest Beatles songs.

Yesterday Mike said: “The house has fond memories, listening to my brother strumming on his guitar by the fireplace, creating his songs.”

Talent “Then he’d bring his mates to the house. John (Lennon) and Paul sat here writing I Saw Her Standing There.”

“They were creating the music that was going to take over the world. It all came from this house.”

Mike said Paul’s talent also stemmed from his musical family, with relatives singing around the piano in the 1950s.

“It was a family institution,” he said. “Dad would get on the piano and all our aunties and uncles would do the harmonies. We used to be the Everly Brothers.”

There are sad memories too as their mother Mary died there in 1956 after an operation. “As a child it rips your heart out,” said Mike.

The National Trust has launched the Forthlin Sessions to mark Sir Paul’s 80th birthday in June and the 60th anniversary of The Beatles’ debut single Love Me Do.