I've been around long enough to have been involved in consultation at the time that the one way in Manor Mount was first introduced. Prior to the one way, it was a major rat run down Manor Mount and David's Road (and vice versa in the morning). David's Road is very narrow and was not infrequently blocked by vehicles meeting half way. Ambulances were then unable to get out of the ambulance station to the South Circular. After several experiments with different one way arrangements the current system was settled on which delighted the residents of Manor Mount and satisfied the ambulance station by removing almost all (legal) through traffic. However it moved the rat run into Ewelme Road, Woodcombe Crescent and Devonshire Road which, IMHO is a much less suitable route. Personally I think the system would work better if the one-way in Manor Mount was reversed, but this would not please the residents of Manor Mount who would get the traffic back from Ewelme.