Emergency vehicle equipment in the United Kingdom

Emergency vehicle equipment is used in the United Kingdom to indicate urgent journeys by an emergency service. This usage is colloquially known as "blues and twos", which refers to the blue lights and the two-tone siren once commonplace (although most sirens now have a range of tones like Wail, Yelp and Phaser). A call-out requiring the use of lights and sirens is often colloquially known as a "blue light run".