Nevertheless, Colquhoun reported to his backers that his force was a success after its first year, and his men had “established their worth by saving £122,000 worth of cargo and by the rescuing of several lives.” Word of this success spread quickly, and the government passed the Marine Police Bill on 28 July 1800, transforming it from a private to public police agency. Colquhoun published a book on the experiment, The Commerce and Policing of the River Thames. It found receptive audiences far outside London, and inspired similar forces in other countries, notably, New York, Dublin, and Sydney.
Historians of policing credit Colquhoun’s innovation as a critical development leading up to Robert Peel’s “new” police three decades later. Along with the Bow Street Runners, the Thames River Police was eventually absorbed by the Metropolitan Police in the 19th century. Colquhoun’s utilitarian approach to the problem – using a cost-benefit analysis to obtain support from businesses standing to benefit – allowed him to achieve what Henry and John Fielding failed for their Bow Street detectives. Unlike the stipendiary system at Bow Street, the river police were full-time, salaried officers prohibited from taking fees.
The idea of a police, as it existed in France, was considered an affront to the liberal English, particularly during this period of upheaval. For the government then, it was not only a matter of saving money, but that there was significant opposition and little support from political constituencies. Colquhoun made an economic rather than political case to show that a police dedicated to crime prevention was “perfectly congenial to the principle of the British constitution.” Moreover, he went so far as to praise the French system, which had reached “the greatest degree of perfection.”
As impressive as Colquhoun’s ability to sell the idea of a publicly funded police force was, his main contribution is recognized as the introduction of crime prevention, or preventive policing, as a fundamental principle to the English police system. His police were to be a deterrent to crime by their permanent presence on the Thames. He arrived at this conclusion by viewing as a science, and in utilitarian fashion, attempted to press that science into the service of the national political economy. He published two dozen treatises on a variety of social problems, but the most significant is his 1797 A Treatise on the Police of the Metropolis.
Thames Division was formed in 1839 with the amalgamation of the Marine Police Force with the Metropolitan Police Force. Initially patrols were conducted in rowing boats, some of which remained in use until 1905. Impetus to change was provided when, on 3 September 1878, the steam collier Bywell Castle ran into the pleasure steamer in Galleons Reach with the loss of over 600 lives. The subsequent inquest and inquiry recommended that Thames Division should have steam launches, as rowing galleys had shown themselves to be inadequate for police duty, and the first two were commissioned in the mid 1880s. By 1898, the force had a further 8 steam launches to supplement its rowing galleys. In 1910 the first motor vessels were introduced. The original Marine Police has been commemorated with police vessel names, including the Supervision launches John Harriott (1947-1963) and Patrick Colquhoun (1963-2003), and Targa duty boats still in use, the John Harriott and the Gabriel Franks.