Carry On Constable transposes the rookies-frustrating-the-boss formula into a police station. Once the film establishes the new men on the beat, it fragments into a series of sketches where one or the other runs into some kind of comic mishap on the job.

The boss is played by the dog-faced Sidney James, who makes his Carry On debut here, and would go on to play the lead (inasmuch as these films have leads at all) in a bit over half the movies in the series. He's a more serious character in this early one, and a nice touch is the glimmer of a romance he has with the great Hattie Jacques. But the rest of the film is pure slapstick, with the misfit cops falling into things and out of things and either chasing or being chased by various animals and irate husbands. There are a few good laughs scattered throughout, but on the whole it's one of the weaker episodes of the series.

After this installment, the list of Carry On regulars would start to become clear. Shirley Eaton and Leslie Phillips, who had each appeared in three of the first four, would not appear again (save Phillips showing up for a minor role in the final episode, 32 years later), leaving Kenneth Williams, Kenneth Connor, Joan Sims, Charles Hawtrey, and Hattie Jacques to solidify their places in the spotlight.