The main reason for cancellation was the loss of government funding.Westland had the Westminster and Belvedere on their books too and only the latter had MoD support. So the Rotodyne and the Westminster( which also had great potential ) got the chop. By then noise wasn't much of an issue....they had developed silencers for the tip jets which actually were only used during the vtol takeoff and landing phase ...they were switched off in the cruise.