I spent a great deal of time on the Avon from 1996 to 1998 when I lived in Warwick.
I caught not only good roach, chub, barbel, dace and pike, I also caught tench and a whopping great crucian carp just upstream of Warwick near the Elmscote Bridge.
For roach, I used to lay on in a near back swim using bread flake or casters. There are some very good roach in the Avon, if you fish into the evenings using bread layed-on, you can at times get a few over 1lb.
My barbel came from Manor farm - Harvington, well downstream of Stratford.
The Avon, like the Thent is becoming more of a specimen river these days. There are very few matches on it know and cormorants are much in evidence in some areas,