At least, that's how I'd hope I'd behave, and that it wouldn't land me in Guantanamo without access to a lawyer or due process. I can certainly see how this kind of aggressive police tactic scares the shit out of people, and they may not know their options or be in a position to think about them clearly. And regardless of what the optimal approach was for Miranda, clearly this was a huge violation of his rights. "Know your rights" isn't a substitute for "they shouldn't abuse them".
But still: when you're detained and you're not sure what to do, default to silence.
1) Not entitled to a lawyer
2) Not entitled to silence
Rights you say... what rights?
Also, if someone tells you that you don't have a right to silence, continue being silent. I know that's easy for me to say from where I'm sitting, but I'm pretty confident it's good advice, even in Heathrow Airport. At least give yourself a chance to beat the system.
They quite clearly denied him access/conversation to his own choice of lawyer. I can't find a clear list of rights allowed to a person held under the act (http://www.legislation.gov.uk/ukpga/2000/11/schedule/7).
It's quite clear from the above who is fully in control and who isn't though - silence will lead to prison and/or a fine.
Or maybe he was lucky if the material was prepared with:
Silence is always an option.
> You do not have to say anything but it may harm your defence if you do not mention, when questioned, something which you later rely on in court. Anything you do say may be given in evidence.
On reading through the CPS guidance linked, the sheer complexity and number of potentially critical missteps someone unaware of the details could make is enlightening.
Say Nothing. Get a Lawyer. (Cue "Never talk to the police" youtube link... I wonder if there is a comprehensive UK equivalent?)