half-blues

(British, law-enforcement) If a police officer is said to be wearing "half-blues", s/he is partly wearing his/her uniform (blues) out in public, but not in their full kit. Usually, this is done when an officer is travelling from/to their place of work. Although this primarily for police officers, the term can be used for other professions where a person is not in full uniform.

Under the current security situation, officers must not be in "half-blues" as directed by the local Superintendent.