Listening to Comfortably Numb the other day, I was interrupted by my beloved exclaiming that she couldn't see the point of guitar solos.

Normally, I tend to let her dismissal of Pink Floyd ("too much noise and a load of lights" was her description of one show) wash over me. But this comment set me wondering: what is the point of a solo? Do they add something indefinable to a song, or is it just a bit of showing off? I think it's somewhere in between - to me someone like Steve Vai is just a skilful poser in search of a good tune, whereas Dave Gilmour or Mark Knopfler create real mood and emotion with just a few notes.

Q once described Neil Young's Arc as "howling feedback madness". Has there even been a better, more evocative description of a rock show full of guitar solos?

I recently caught half a Van Morrison gig on BBC4 and have to say, not speaking as a fan, that I was baffled as to how the man remains popular.

His performance was appalling. The end of one song degenerated into mumbling so inaudible that it was practically silent, and the clearly bemused band were obviously wondering how long to keep strumming for before the great man called a halt.

And after Van thanked some of his musicians (but not all, for some reason), the final number closed with him stumbling off stage bent over like a old woman with heavy shopping, leaving the band - who were on top form throughout, with a professionalism that put him to shame - to play on without the star of the show until they finished.

So, with a sense of genuine interest, I ask: what is the fuss all about? Did I just catch Mr Grumpy Trousers on a night when he decided to impersonate a bad pub singer? He obviously has something, given the number of fans he has in this parish, but what is it? I ask because my better half was thinking of buying an album of his or two, and we want to know which CDs among his impressively large collection are worth checking out. If any...