Dratsab:
Hmm - some good, some bad here. The article you didn't link to is a little out of date in that it says "The police will search an offender's bag upon arrest" - actually police will search your bag (under the Search and Surveillance Act 2012) if they have reasonable grounds to believe (as opposed to justifiable cause) an offence has been committed and the search will locate evidential material in relation to this. Such a search could be by consent (s92) or not (s88).
If someone wishes to serve a trespass notice on you and you refuse to provide your details you're actually on the path to committing an offence under s9 Trespass Act 1980.
BTW - there is no such thing as citizens arrest. It's very much a misnomer and I challenge you to find any reference to it in the Crimes Act. There is only 'arrest'.
Not that I particularly care one way or another - just thought I'd steer things in the right direction.
cheers for the info
a couple of comments....
1. re search - police do, with reasonable grounds - store staff do not
note: and plod needs a good reason too - i have denied a personal search when they did an id check at a pub, i was young, legal - but fair enough re the query - i was polite, gave them my id, when they tried to reach into my pockets i moved away and said no you don't - they stopped as they knew they did not have reasonable grounds
yet every day people give this right away :/
2. tresspass notice - i may be on that "path" - but again without reasonable cause (standing in a shop, telling a muppet to cooperate with police in my view is not reasonable cause, and the boys in blue agreed when they got to the store - muppet pie stealer got trespassed - i did not)
so i ain't worried about jack - and i stand by the fact the STORE cannot serve a notice on a john doe - plod however can move things along - but this was not the case here
for the record - i have family who are lawyers (prosecution and defence) and a brother in law soon to be a boy in blue (well done that man) - and respect them and all that they do - so this ain't about hatin on the MAN - it's about knowing your rights, not giving them away to the police and especially not to other private citizens - and respect both ways