An interesting question. I moor at Osney and have never needed to wind above the lock, but it always feels narrow there even for my 52 ft boat. The widest bit I think is by the upstream marina entrance halfway along East Street. Otherwise, given the direction you're travelling, tie up to the bank upstream of Sheepwash channel. There are plenty of gaps between the trees and it's nice and quiet. It's also barely any further into town than E Street, there's a path straight to the station.