Some early-19th-century references to "railway police" or "policemen" do not concern constables but instead describe the men responsible for the signalling and control of the movement of trains (it is still common colloquial practice within railway staff for their modern equivalents in signal boxes and signalling centres to be called "Bobbies"). These personnel carried out their duties mostly in the open beside the track and were often dressed in a similar manner (e.g. a top hat and frock coat) to early police constables but were not directly concerned with law enforcement. Historical references (including those originating from the BTP itself) to when the first group of true "constables" was organised to patrol a railway should be treated with caution. This warning is repeated by the Metropolitan Police Service (MPS) webpage dealing with MPS records of service which on the matter of records of other forces held by the Public Record Office (now the National Archives) states: "The occasional references to 'Police Department' in the railway staff records relate to signalmen etc., although some were simultaneously county constables."