Hi,
I run Nappy Valley Nannies and at the moment the going rates for a share depend on how much experience a nanny has as apposed to childrens ages etc. The current salary expectations are between £11 net per hour for a nanny with around 5 years experience and £12 per hr for nannies with 5+ we do have some nannies who have around 15 to 20 years experience who can sometimes ask for £13 ph.
Hope this helps!!
Good luck too