I wouldn't be in favour of taking children away from depressed Mothers, in fact in previous professional life, did a lot to promote the rights of Mums with mental illnesses to look after their children.
However, if you are paying some one to look after your children, you would want them to get the best care, maybe the Mum only sees the Nanny for a short time in the morning and evening, and seeing the Nanny for a good couple of hours with the children at the group, might be more informative.
Still haven't decided what I will do, but even if I do speak to Nanny or Mum, the worse I can do is offend surely?
My Mum suffered from depression by the way, and i do think that if it goes on for a period of time, it can have quite a powerful effect on children. There is plenty of research to back this up.
Surely if the Nanny isn't doing her job well, just like any job, if the reason is mental health problems she should be entitled to support like any one else. I am not suggesting I think the MUm should just drop her, but as I don't know the Mum, I don't know what she would do with the information.
Thanks for all your responses anyway