Hi Mancuso, <br />
For buying, selling ,renting or promoting a home a real estate agent can help protect your interests and potentially save you a substantial amount of money and time. They make this task a lot easier for us. So for their services you have to pay their charges in terms of a commission. <br />
There are many high profile estate agents that source major portfolios and developments like Plaza Estates in London and they provide a comprehensive list of properties for sale as well as rent in your required choice of location.
Different company has different criteria and it charge according to it, there is certain fees, which is charged by the different company as per their criteria. One should be little careful while paying the company that they should not change too much money for promoting the services and to get London property search agents.