Scotland Yard said in a statement that it is “unusual for a single plain clothes police officer to engage with anyone in London”, although it can happen.
They said that an lone officer could be seeking to arrest you, but if they do then you should “expect to see other officers arrive shortly afterwards”.
As of yesterday the Metropolitan Police announced they would not deploy plain clothes officers on their own.
Deputy Commissioner Sir Stephen House said: “We will not operate plain clothes officers on their own. If we do use them, they will be in pairs.”
However he said there will be “occasions” where that is not possible – such as when a pair of officers are split up – and noted that off-duty officers [will] not [be] in uniform. …
You would expect a lone police officer who is arresting you to soon be joined by backup, although it is possible that this might not happen and you are still alone.
Scotland Yard said in this case that it was “entirely reasonable for you to seek further reassurance of that officer’s identity and intentions”.
The Met said it advises people to “ask some very searching questions of that officer”, including:
~ “Where are your colleagues?”
~ “Where have you come from?”
~ “Why are you here?”
~ “Exactly why are you stopping or talking to me?”
Former Scotland Yard Senior Officer Parm Sandhu told ITV’s Good Morning Britain that there were things people could do if they were concerned about an arrest.
She said that people should not get into the vehicle unless it’s a marked police vehicle and ask to see the radio, or ask the arresting officer to call their colleagues and make sure they are on duty. She added: “If you’re really concerned dial 999.”