Mr Dowd did say that buses should continue to use the road, it is only cars and lorries that would be diverted. I assume this would allow for the pavement to be widened to remove the bus lane.
The A205 would need to go up Kirkdale and either down Dartmouth Road or through Sydenham and down Perry Hill. I don't think Dartmouth Road is wide enough to deal with this level of traffic (it is bearly wide enough in places for two buses to pass each other), so we will have to generously allow Sydenham to have all the lorries from the South Circular.