My nanny was in Redcliffe Gardens yesterday morning (Earls Court) and saw another nanny slap and then violently twist the nose of a young boy of 2-3 years as a punishment. She came back home and asked me what she should do - obviously if this is happening in public then what happens behind closed doors is unimaginable.
For those who might know someone in the area, the boy seemed French ("Merci") and had shoulder length hair. The nanny was probably in her 30s, of African descent and was wearing black leggings.
Sorry for the vague request, but I find this quite galling and want to do something to help. I've been at a loss about what to recommend, short of keeping her phone camera locked and loaded for the next occasion.