1. A method of operating a computer system in order to retrieve information from two or more heterogeneous distributed databases of different formats, said computer system including a policy store storing one or more policies, said method comprising: providing a user interface to said policy store enabling user configuration of said policy store with one or more policies; each policy declaring one or more software modules required for processing a query; wherein each software module is operable to interact with one of said heterogeneous databases in order to retrieve said information; receiving a query detailing information derivable from two or more of said databases; responsive to receipt of said query: a) searching in the policy store for one or more policies associated with said query and b) running the software modules declared in the one or more policies in order to retrieve said information from the two or more of said plurality of databases.