1. A computer program product comprising a computer program operable to control a computer to access a computer file, said computer program comprising: (i) file characterising logic operable to detect at least one characteristic of said computer file; (ii) cache hint selecting logic operable in dependence upon said at least one characteristic to select from among a plurality of different possible cache hints a selected cache hint to use in association with said access to said computer file; and (iii) file access request issuing logic operable to issue to an operating system a file access request for said computer file accompanied by said selected cache hint.