Note: Mobile Surveillance Officers (Ref 98).
recruitmentservices.applicationtrack.com/vx/lang-en-GB/mobile-0/appcentre-1/brand-2/xf-5776cecd133e/candidate/so/pm/1/pl/4/opp/98-Mobile-Surveillance-Officers-Ref-98/en-GB
(sub-section heading "Ability to blend in" in the section "The skills")
Another sub-section heading in the same section: “Thinking on your feet”
(a) think on one's feet: "Fig. to be able to speak and reason well while (standing and talking) in front of an audience, especially extemporaneously"
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs, 2002,
idioms.thefreedictionary.com/think+on+feet
(b) think on your feet: "to think and react quickly, esp having good answers ready <When you’re called on in class, you have to be able to think on your feet>"
dictionary.cambridge.org/us/dictionary/american-english/think-on-your-feet
--------------------------------Separately
Well, UK Secret Service is also recruiting Chinese and Russian speakers. In its job application website:
recruitmentservices.applicationtrack.com/vx/lang-en-GB/mobile-0/appcentre-1/brand-2/xf-910ce594c205/candidate/jobboard/vacancy/1