Real quality is so limited these days. I hate paying £300 to £450 an hour for a good agency girl, but the pricing in London has gone up so much over the last few years, driven by the increases in cost of living, particularly rent increases.
A girl charging £350 an hour is paying 45%, 15% to a manager and 30% to the agency that delivers the job plus £800 plus a week for what is often no more than a grotty bedsit. Financially the girls can do as well at home and better in Dubai etc. leaving London as a distant poor cousin.