Thanks for the link - useful. I still think this hop might be partially involved though, perhaps in combination with my water (which I don't filter and is a little chlorine tasting!) Thing is my other beers are good using the same water. My typical bittering hop is Magnum or Chinook for IPAs, or for less hoppy beers Willamette, Goldings etc.
Every one that has been a little suspect has had Sorachi Ace as the bittering hop. Phenolic is definitely the term.
OK so I have an IPA in secondary now ready to keg on Monday and I used Sorachi Ace as the bittering hop for this beer so I'll look specifically for this taste in that.
Next thing to do is brew one of the suspect beers again and use a different bittering hop. And possibly brewing the same one again with filtered water.
Looks like I have some work to do ... anyone else use Sorachi Ace in non Belgian beers?