The etymology of the word "police" supports your British security forces notion (with the addition of the Marine aspect): http://www.etymonline.com/index.php?&

The etymology of the word "police" supports your British security forces notion (with the addition of the Marine aspect): http://www.etymonline.com/index.php?&search=police http://www.etymonline.com/index.php?&search=police police (n.) c.1530, at first essentially the same word as policy (n.1); from Middle French police (late 15c.), from Latin politia "civil administration," from Greek polis "city" (see polis). Until mid-19c. used in England for "civil administration;" application to "administration of public order" (1716) is from French (late 17c.), and originally in English referred to France or other foreign nations. The first force so-named in England was the Marine Police, set up 1798 to protect merchandise at the Port of London.