1. A cache system for operating between a processor and a main memory of a computer, the cache system comprising: a cache memory having a set of cache partitions, each cache partition comprising a plurality of addressable storage locations for holding items fetched from said main memory for use by the processor, a cache refill mechanism arranged to fetch an item from the main memory and to load said item into the cache memory at one of said addressable storage locations; a cache partition access table holding in association with addresses of items to be cached respective multi-bit partition indicators identifying into which cache partition the item may be loaded, wherein the cache refill mechanism is operable to allocate to each said item fetched from the main memory one or more of said cache partitions in dependence on the address of said item in the main memory.