I once shared lunch with the great music producer, Sir George Martin, often called "the fifth Beatle" for his work on the Fab Four's albums. He was charming, erudite and happily indiscreet. Asked to name the most talented musician with whom he ever worked, he was blunt. "It's Paul, but no one gives him credit for it."

I remembered Sir George's words yesterday while puzzling over why so many are begrudging in praise for Sir Paul McCartney, surely Britain's greatest living pop culture treasure. His 70th birthday brought the usual deluge of affection from a public, for whom the Beatles' music was the soundtrack of their lives, but the critics were less keen. Yes, the man gave us "Ebony and Ivory"; sure, he wrote the infamous Frog Chorus song. Maybe the last 20 years have been a bit hit or miss, and, OK, his voice at 69 was a little thin at the Jubilee concert, but...

Macca has sold over 100 million singles and 100 million albums. His "Yesterday" is the most covered song of all time. He was half of the finest song-writing duo of our era, and he is a fine bassist, and accomplished guitarist, pianist and drummer.

His real problem was to live on. As Lennon and Harrison died young, like Hendrix, Jones and Morrison, they were never the embarrassing "dad at the disco" Macca turned into. In McCartney, as much as any other living being (the Queen?) millions of baby boomers see their own ageing reflected back at them. It is arguably the hardest of all tricks for an artist, longevity, and I think Sir Paul has actually pulled it off pretty well.

I wrote "arguably", because an even tougher trick is to write or co-write 43 songs that have sold more than a million copies. That alone earns you the right to a double thumbs-up and a little respect, doesn't it? "Cool"!

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