In this thesis the process by which crime investigation, detection and prosecution became an integral function of the British police service is analysed through an examination of public records, contemporary papers and documents, and by reference to the literature on policing. The impact of the adoption of that function on the role, organisation and management of modem British policing is then assessed. It is established that at its foundation by Robert Peel's Metropolitan Police Act of 1829, the British professional police service was intended to be a purely preventive and protective body of uniformed patrolling constables. The function of crime investigation, detection and criminal prosecution was then subsequently added to its responsibilities by government using administrative rather than any democratic or legislative means, thus creating the present dual crime prevention and crime detection role of the police. Major recurrentp roblemse xperiencedb y the modemB ritish police servicea re identified as arising from that change in its original functions and purposes, and proposals for action to resolve them are set out.