Evenin' all,
With regard to powers of arrest, any person may arrest without warrant any person committing an arrestable offence, or about to commit such an offence, or anyone who is guilty of an arrestable offence, or whom he has reasonable grounds for suspecting he is guilty of the offence.
What is important here, is the nature of the offence. Not all offences carry a power of arrest. The obvious ones such as theft, criminal damage etc, are arrestable, so ANYONE could arrest, for example, a person they see stealing from a shop.
Other offences such as fishing without a valid licence, are not arrestable. If you don't carry your licence and refuse to give your details to a bailiff who requests them , then you could be arrested, but only by a police officer, under S25 PACE 1984, not the bailiff.
As for bailiffs carrying handcuffs, etc, then they are putting themselves on a sticky wicket. Common law does allow you to use force to protect yourself, and property, and to prevent offences being committed, but any bailiff who starts down this road without fully understanding the law, could find himself being arrested for false imprisonment, if he decides to handcuff someone who gets arsey with him when checking licences.
If in doubt, when approached by a bailiff who starts getting a bit tasty, ask him to call the police, and see what happens.
I am trained in the use of force, and can stand in the witness box to justify a baton strike, using handcuffs, and CS spray. I use the law every day, and know what to expect if I get it wrong....
Arresting someone, is about as serious as it gets, especially if you are in the wrong. The human rights act has made sure of this.
I'll happily answer any more questions if anyone wants to know more,
Tommo