About 12 years ago I used to live in a ground floor appartment on Ray Mead road in Maidenhead, that overlooked the Thames between Boulters Lock and Maidenhead bridge.
I often used to see coarse anglers fishing from the pavement in front of my flat (where you only needed an EA license) and would wander out and chat to them from time to time.
They fished for and caught a whole range of different species, but I often witnessed them catch Barbel in the 2-3 lb range, sometimes larger.
Unfortunately I was not as avidly in to fishing in those days so I can't tell you what rigs they were using, but I seem to remember they mostly used ledger techniques.
Not sure if it is still the case, but it might be worth you asking around anyone who fishes that section.
And whilst not quite so close, St Patricks's stream and the River Loddon at Charvil are both noted for holding quality barbel. Suggest you look at Twyford and District Fishing Club
http://www.tdfc.org.uk/fisheries.htm.
Cheers,
--
Bill.