No, there are not. There are a lot of ads with those rates, but most roles are ~ £450. Please note that a single contract goes out to many agencies that post the same contract, so you might think that there is a lot of £600+ roles. While in reality there is a lot of people posting the same role X^N times.
Some of those posts are not even real roles - new guys in agencies need to collect a lot of CVs, so they post bogus £600 contract and collect your CVs as "stuffing" for their "portfolio"
£700 are rates for an experienced core Java developer with investment banking or FX experience.