Fowler infiltrating the bank robbery in "Rag Week" by disguising himself as the pizza delivery boy the police had called in, then calmly ordering them to turn over their guns. (Of course, he thinks they're just university students pulling a Rag Week prank, but still.)
Patricia dealing with the catcalling builders in "Come On You Blues"
[As Patricia goes to walk into the bank, the builders start catcalling.]
PATRICIA: You want me to get them off? [noises of assent] Right! [She opens her coat, revealing her police uniform] You're all under arrest!
Raymond and co. busting the pub lock-in in "Alternative Culture" after Grim refuses to let Habib off for withholding evidence to protect her sister. Grim and Boyle try to escape through the bathroom (which Boyle claims is an "old coppers' trick"), only to find Raymond waiting for them.
RAYMOND: The problem with old coppers' tricks, Constable Boyle, is that old coppers know 'em.
Goody (of all people) in "Kids Today" gets one, when he punches out a teenage skinhead for racially abusing Habib.