Six days after the Princess Diana concert had 15 million viewers, another day-long musical extravaganza was live from Wembley! It couldn’t lose, right? Wrong.

Al Gore’s eco-concert peaked with just 4.5 million viewers on Saturday night. This of course had quite a lot to do with the weather, the sun coming out just in time for the concert about global warming.

But what is it about a Diana concert that makes 15 million people tune in, but a concert to save the world gets less than 5 million?

If I was a betting woman - the world of overnights is surely ripe for spread betting - I would have had Live Earth getting far more many viewers than a concert for Diana. It had more stars, stacks of pre-publicity and the BBC rolled out its big guns in the shape of £18 million man Jonathan Ross and, er… Graham Norton.

But the nation remained unmoved. Maybe two concerts in a week from Wembley is too much for the viewing public. Certainly two appearances by Ricky Gervais at Wembley was far too much for me. At least he didn’t sing this time round.

What do you think?