Vauxhall Vectra vibration/resonance

As vehicle speed increases, there is an increasing vibration/resonance that appears to come from the front nearside of the car. Between 45 and 50mph, the resonance/vibration reaches its peak and remains at this level even if the vehicle speed increases. If you allow the car to "coast" the resonance/vibration reduces as the vehicle speed decays. The resonance is not affected by engine rpm. Have replaced all discs and pads and nearside driveshaft, no change. Just gone through MOT so assume wheel bearings are ok as they have not been picked up. Is there anything else I could check?