If Railway Inspectors are "detaining" people with a view to questioning them about a possible fraud (an intentional failure to purchase a ticket) then surely that is the time when the caution should be given. Do you know what is happening at this "initial interview" you mentioned? If it is about the possibility of a passenger not being in possession of a valid ticket, I would expect a formal caution to be given then. The interview clearly is in relation to the investigation of a criminal offence (to which the provisions of PACE apply and perforce the Codes of Practice). Before anyone who is particularly sensitive gets upset by being called a 'suspect', that is the correct term as defined by these rules in referring to someone who is suspected of having committed an offence.
Additionally, do Railway Inspectors have a power of arrest (other than a so-called Citizen's Arrest)? I don't know if they do (I suspect not). Maybe if a few passengers were read their rights, especially if they watch a lot of American Cop shows, they - and others - may be more inclined to buy a ticket!
The rubbish that is 'American Cop jargon' is one of the things that really confuses people in my experience.
A majority of people these days seem to refer to being 'read my rights' rather than being 'Cautioned', which is of course the correct term.
Yes, all inspectors of my acquaintance are trained to Caution the 'suspect' in line with P.A.C.E. (1984) Codes of Practice as soon as they believe that an offence has been committed, they must ensure that the person being questioned understands the caution and to make contemporaneous notes throughout the questioning, which will be read aloud to that person on completion and an opportunity to sign them should be given.
If the person being cautioned indicates that they do not understand then an explanation of what the caution means can be given. It is not essential to caution a person in order to report an offence, but a failure to do so may mean that any comments made during questioning might not be taken in to consideration in Court at a later date.
This authority to caution is not restricted to Police officers as suggested by
soil. It is a procedure to be followed by many investigators engaged in interviewing to gather evidence to report crime.
Yes, there is still a specific 'power' of arrest under Section 5.2 of the Regulation of Railways Act (1889) in certain circumstances, but inspectors will normally seek Police assistance where a need to arrest is thought by the inspector to be essential.