Tring Anglers have waters on the Thame, Ouse and Ivel (I think).
I'm not sure if there are any trout but there should be some chub, dace or possibly carp action. They also seem to have a bit of the Windrush and this river does hold trout and a few grayling in places.
Here they are:
http://www.sensetech.me.uk/tta/1home.php
I also think that there's a bit of river trout fishing around the Tring reservoirs, one of which is or was a stocked trout fishery run by a syndicate. Try Mr Google.
Happy hunting.
Gudgeon