dubdisciple
"Beat It" may not be Eddie Van Halen's best solo but is without a doubt the song he played on that had the most gross sales.
 

 
'Beat It' was included for Steve Lukather's riff, I remember that because the presenter on the 'countdown' for this list couldn't pronounce Lukather.

craigb
 
 No Cars by Gary Numan?.... 
 
....doesn't really know what a guitar riff is!

The list is part of the BBC's Guitar Season.  It was compiled from votes/suggestions by BBC radio listeners.
 
You have to look at the list in terms of the main guitar riff,  not the song or band. The riff may only be 1 or 2 bars, but if it's soooo good everyone remembers it, then it will make the list.  There are some pretty iconic riffs there...
 
I didn't take part so I didn't see the rules of entry, but it is plainly obvious that it's limited to one entry per band/artist.
If Black Dog isn't there it's because not enough people voted for it. It may be the best riff evah but Whole Lotta Love was used for years as the theme tune to Top of the Pops and EVERYONE who listens to Radio 2 in UK knows it...

jamesg1213

craigb
 
 No Cars by Gary Numan?.... 
 
....doesn't really know what a guitar riff is!

I wondered if anyone would catch that. 

I thought it was quite refreshing to see things like 'Riverboat Song' and 'How Soon is Now' alongside the old standards. Nice to see my all time fave at No 3.

How Soon Is Now used to win this competition 15 years ago.