 The Royal Navy first installed RPC, experimentally, aboard HMS "Champion" in 1928.In the 1930s RPC was used for naval searchlight control and during WW2 it was progressively installed on pom-pom mounts and directors, 4-inch, 4.5-inch and 5.25-inch gun mounts.During their long service life, rangekeepers were updated often as technology advanced, and by World War II they were a critical part of an integrated fire control system.