Reading some of these replies it seems that on rare days the roach really av'it.
I remember 2 of these 'special days' on the Thames.
One was a match at Child Beale near Reading about 10 years ago.
An autumn day where every peg bagged up with clonking roach.
February 2007 I fished the same venue and the same happened again.
We were casting out feeders of GB and pinkies on the hook. The feeder barely settled and the tip was nodding.
I'm convinced that there are big roach present in all manner of venues but some very rare days all the conditions seem absolutely sock on and the roach go ballistic.
A good rate of flow seems to be a major factor but some days it doesn't help?
It must be a combination of flow, air pressure and light values
?
I wish I could predict these days but for the life of me I can't.