George Harrison's son felt a ''tremendous responsibility'' to release his late father's work.

The Beatles legend was working on a career retrospective when he passed away in 2001, so 36-year-old Dhani Harrison took over the project and felt the pressure to get as much of his dad's music heard as possible.

George's widow, Olivia Harrison, said: ''He wanted his music out. George was just embarking on that retrospective of his musical life - he never called it a career, he said that was the wrong word for him - but time ran out and he died.

''Dhani wanted to do it and felt a tremendous responsibility to do it. There's still a huge archive of material that still needs working on. You can't just let tapes degrade and never be heard again.''

In the sleeve notes for new compilation 'The Apple Years 1968-75' Dhani admits he learned a lot about his father while putting it together, a revelation which surprised his mother, though she herself was always astonished by how ''intimate'' George's lyrics were.

She told The Times newspaper: ''I thought George shared a lot with Dhani, much more. Maybe it was a prescient thought of, 'I'm not going to hold anything back'. He really did give him a lot of instruction on everything in life so I don't know what Dhani's thinking about there.

He did express a lot in his music that he didn't express in life. He wouldn't want to talk about things but he would write a song that had more personal revelations in it than I would ever want to say. I would think, 'How could you say that? It's so intimate' but that was his way of expressing himself. Thank goodness he did.''