It also depends on the situation....
If it's just straight babysitting for one child, say aged 4, for a few hours, then its usually £4-5 an hour for me.
But you have to take into account other factors, like I'm CRB checked, first aid trained, with loads of previous experience and 4 child care qualifications which bumps up the price of hiring me.... whereas say a person with no first aid training, no CRB check and not a lot of experience would expect to be paid less....
It depends on the family as well, some pay you well, and some don't. It also depends on the CHILD you are babysitting, for example, newborns, twins, children with learning disabilities, or more than one child, that can also bump the rate per hour up seeing as it's more effort and work involved.... it also depends on the situation, for example, tonight I'm babysitting ONE child aged 9, so wouldn't be any extra than my usual rate, usually, however I am babysitting her in a hotel room as she sleeps, she went to a wedding today and her parents want to go to the reception alone from 9pm-1am which is in the hotel, so the charge is more because it was a last minute decision and in a strange place.....
=] hope that helps!