I always find it odd that if you miss a train going through Forest Hill, you have to wait until after the New Cross and Clapham Junction trains for the next West Croydon or Crystal Palace train. Wouldn't it make more sense to alternate these services so you only had to wait for one train to go through or is this too simple?
That is what they're appearing to be doing with the change to the timetable.
A look at Real Train Trains for Wednesday 16th December shows the new service pattern at 1700 at Canada Water.
1701 West Croydon
1706 Clapham Junction
1709 Crystal Palace
1712 New Cross
This means a wait of seven minutes per train to Forest Hill and HOP instead of the current 5 min gap between the West Croydon and Crystal Palace trains, then 10 mins before the next West Croydon.
Northbound trains will operate every seven minutes from Forest Hill to Highbury and Islington.
Southern trains from Forest Hill to London Bridge will operate off-peak at x15, x22, x45 and x52. This means Southern services will operate at uneven times off-peak due to Victoria services starting earlier.