Do gun foils not count as police units? I started a game as the Pirates and noticed that once my HQ base reached size 2 I had a drone despite the presence of the unity gunship I started with; this was also the case at my second base with the gunship I built there.

Even though 'realism' is hardly consistent in this game, perhaps in this case they realized ships cannot patrol the streets of a city.

but then again, if were talking realism, perhaps ships can patrol the streets... Vienna does come to mind, and this IS an ocean colony??

I don´t remember how it is named correctly, but is your policies allowing police units?

It would depend on your fraction and their values how many police units you need to supress one drone. And also on your research ;)

AFAIR every unit counts, but with different policies, you can increase/decrease the number of drones.

Manual is downstairs to look it up, sorry

Also i would strongly recommend considering unconventional ways of increasing the difficulty level other than the 'actual' difficulty level which sucks because of its huge brown nosing of drone happiness. Such ways as, play Morganites, give all the AI monsoon jungles, give the AI good starting locations with plenty of territory, but less territory for yourself, etc etc

Experiment and find out.