Don't wish to be pedantic but you can't have £40 per hour as a minimum AND an average because, as Whirly states, she is getting £30 per hour which will bring down the average (and is obviously the minimum!!)
However, if £40 is the average, it implies there are some people getting more than that so some negotiation is in order.
Cheers
Whirls
Actually, I love being pedantic! Sorry!