The argument would be whether part B of the code is a relevant requirement, considering
"This Code of Practice deals with police powers to:
• search premises
• seize and retain property found on premises and persons"
Two words there ... search and sieze.
As investigating officers, you do not search premises neither do you sieze goods/articles/items. You inspect and gather evidence using photographs (hopefully) but shoud have regard to the code in case of procedural challenge. You powers of entry and inspection are under Article 27 of the order .... unless you think you have the authority to actively look for offences.
I have argued successfully to persons more senior and experienced than myself that a code B notice was not needed during an investigation and indeed, at all. Service procedures can be used to record this fact and state the reasons why (back to procedural challenge)
With regard to cautioning, I would say that timing is everything.
If you caution a 'suspect' because you have
reason to believe an offence has been committed, you will be doing alot of writing. Following the caution, every question you ask and the answers the suspect gives
must be recorded verbatim. Ask one question and that constitutes an interview .... dodgy if not done under caution and things will become complicated!
Why caution at the time? Remember that the RR(FS)O is criminal law, therfore the prosecution must prove beyond reasonable doubt that the offence has been committed and present the evidence accordingly.
If you are investigating and gathering evidence, you don't need to caution so can ask questions in relation to fact finding as long as this is recorded in your notebook. When you have done, get the person to sign as a true record of events at the time. If you proceed, then this is admissable evidence in court.
If you do caution, it is your responsibility to ensure that the person fully understands the caution. Miss this point and their brief may get you on a technicality and abuse of procedure!!
You only need to caution if the person makes a significant statement which is an admission of the offence or you want to halt an inspection due to obvious evidence and you need to conduct a proper interview at a suitable location, conducted in a proper manner ... recorded and with representation.
It is best to only caution at the interview stage and when you have evidence to put before the person which you seek answers to.
It's a potential minefield which needs to be trodden carefully, not that I have any experience!!