I think Cheeky makes a very good point and the removal of just a couple of parking spaces would make a fair amount of difference.
I think there is another problem which is the timing of the lights for going straight on from HOP at this junction. I would be interested to know how long is allowed during the day and at peak hours, if anybody fancies timing them, or it is all controlled by a camera sensor that is not doing its job correctly?

Google street view shows a ghost bus stop across the road which takes up most of the other lane. I wonder if this has a negative impact on traffic or if it is just never used.

A related point is that it might be possible to bring forward the stopping line for cars waiting to turn out of HOP.

Does this have an impact on the P4 as well as car drivers? TfL and Lewisham more interested in minor changes such as this if it might impact buses rather than cars. If it does impact buses then it is an ideal issue for me to take to the Lewisham Public Transport Liaison Committee on behalf of the Forest Hill Society. But it would be useful to have the additional details outlined above.