Going rate for baby sitters

[usernametaken]

What is the going rate for a young baby sitter´?
I'm not sure if the girl (our neighbour) is 14 or 15 but she'd love to baby sit every so often. I have no idea how much baby sitters earn. She would have 2 kids to look after who would already be in bed and hopefully asleep when she gets here.
Many thanks.

We are paying the teen who s babysitting tonight (woohoo) ten pounds. She will be here a couple of hours maybe longer but flat fee. Hopefully sky movies, snacks etc make it worthwhile for her. DSs will sleep in sofa bed in adjoining room so technically in bed. They have been warned to stay in bed whilst watching DVD to make bsbysitting easier.

£10 sounds good. She can help herself to whatever we leave, the kids will be in bed and she can jump through the hedge to get home...perfect. Thank you!