Bailiffs and private companies have no power to arrest suspects, or debtors, let alone detain and transport prisoners.
It is the practice of some bailiffs to use police-like terminology when confronting debtors.
If a bailiff gets into a fight with a debtor, the bailiff commits a breach of the peace.[1][2]
A power to use force does not include power to use force against people,[3] and anyone being attacked may use reasonable force for purposes of self-defence.[4]
If a bailiff puts a document through your door saying he can arrest you, then you do not need to respond to it. It is a bailiff trying to trace a missing debtor.
The document may be handed to police by reporting an offence online through your local police force website.
[1] Justices of the Peace Act 1361
[2] Regina v Howell [1982] 1 QB 416, [1982] QB 416, [1981] 73 Crim App R 31
[3] Paragraph 24(2) of Schedule 12 of the Tribunals, Courts and Enforcement Act 2007
[4] Section 76 of the Criminal Justice and Immigration Act 2008
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