"I wanted to work with that idea, so it was somehow very simple. I was trying to get my feelings for her into it."

Linda McCartney

Sir Paul and the composers attended a live concert, featuring all the works on the CD, at St Andrew's Church in central London.

Proceeds from the album, which features eight original compositions and one by Ralph Vaughan Williams, will go to the Garland appeal, which aims to raise �2m to help cancer research through the healing power of music.

Sir Paul, whose composition ends with the word Amen, said it also reflected his spiritual side, but was not intended to be religious.

He said: "I have a certain kind of feeling that's not so much religion, but includes God and spirituality.

"I think maybe a song, Eleanor Rigby, explored that."

I think it was what I was feeling about Linda at the time and I just wanted to somehow include her spirit of goodness.

Sir Paul McCartney

He said he believed Linda would have "loved" the new album as it was a "very special thing".

Sir Paul added that she had had to use a computer program to help him write the music because of the weaknesses of his sight-reading skills.

He said: "Although I'm not normally very computer minded, I wrote it on that."

Sir Paul's fellow composers also spoke of their pride at the finished result of the project.

Sir Paul and Linda McCartney

Praising the marriage of classical and pop music, Sir John Tavener said: "This is wonderful. Perhaps we can go back to what music originally was."

Judith Bingham added: "Paul really sticks out like a sore thumb and he's the one who's standing out on the cliff top there being judged, rather than us."

A Garland for Linda was first premiered at Charterhouse in Surrey in July last year, a performance which officially launched the Garland appeal.

The aim is to stage it at least 200 times worldwide during the next three years.

Linda McCartney died aged 56 in April 1998 at the McCartney family's Arizona estate.

The album is released by EMI Classics on 7 February.