Sir Paul McCartney still uses John Lennon as a ''judge'' of his songwriting.

The Beatles legend admits he will scrap lyrics if he doesn't think his late bandmate - who was assassinated in 1980 - would have approved of them.

He said: ''I imagine myself back into a room with John, and I'll think [about a lyric], 'Ugh, that's no good.' And I'll imagine him saying, 'No, can't do that.' So I'm using him as a sort of judge of what I'm doing.''

The 72-year-old musician found himself feeling emotional at his wife Nancy's 55th birthday party in Tokyo last month because the guests were entertained by Queen and Beatles tribute bands and he was overwhelmed by the uniting power of music.

He explained to Billboard: ''I had a kind of very emotional moment when we were sitting there - it could have been the alcohol.

''And I'm thinking, 'My God.' The power of British music finally came home to me. All the way across the world, in Japan, these guys were breaking down Queen songs, and the others Beatles songs. They were replicating them amazingly. They got all the orchestra parts on 'I Am the Walrus.' They may not even speak the language that well, but they speak these songs beautifully.

''I should know that we've had that effect, because it's historically true. But it doesn't always come home to you in quite the way it did that night. I was welling up and I was [thinking] 'I can't well up to a Queen tribute band.'''