I find Devonshire Rd hit and miss to be honest. Some days its quiet, other days can take 10-15 mins to get out of.
I do think that Church Rise being used for the diversion rather than Westbourne would have eased the congestion, preventing the build up on the corner of PV by the Co-Op, but thats a bit late suggesting now, and CR is split, where Westbourne is one road.

With regards to the lights up London Road, I do think something has changed on the timing there. The tailbacks along the A205 reaching back to Dulwich Village, is causing the traffic to go up via Lordship Lane, and round the back to Canobie, Tyson then Devonshire.

All ending up sadly in a stationary Forest Hill.

Lets see what happens next week with PV hopefully reopening. Progress looks good there I must say.