Sorry to hear about this bonobo - not a nice thing to happen.

Not sure if this could be related or not, but I was walking back with the dog from the recreation ground at lunchtime today (14.30) and passed a guy matching your assailant's description on Grierson Road just down from the junction with Honor Oak Park. I'd go so far as to say he was loitering - certainly acting suspiciously (looking into car windows, checking over his shoulder etc) - I was concerned enough to take note of some details (before reading your post) which might help/jog your memory:

- Grey beanie
- Olive green jacket
- Grey Nike tracksuit bottoms (with embroidered logo on back of right leg at shin height)
- Grey shoes (canvas trainers)
- Tall, approx 6ft 3
- Clean-shaven, black and aged approximately 30