A mortgage broker can undoubtedly reduce the rates you'll pay on your mortgage, but interest rates are just one element of the cost of a mortgage - other factors include:
Arrangement fees
Product costs
Exit penalties
Revolution will compare product costs on a like-for-like basis (even if the fee structures are very different.
This service ensures you not only have the benefit of an experienced broker negotiating your rates directly with your lender but can also make informed choices about which mortgage offer is right for you.