@ Matt, James, Dot tild dot,
"Of course, if you've got nothing to hide, you've got nothing to worry about *cough cough*"
Asside from the old barister trick of missdirecting a jury (prove you don't...) the Police have latched onto the idea of how "technology" can make inoccent people appear guilty of whatever they decide.
It works this way,
In London most people have mobile phones, credit cards, travel cards, store loyalty cards and ID/Key cards or "punch in" etc.
All of these leave a nice audit trail of not only of when but where you have been.
Most inoccent people cannot tell you without the assistance of supporting documentation (Diary / recipts / itemised billing etc). accept in the very broadest of terms where they have been and when. If it is more than a week ago let alone a month or a year most have absoulutly no chance unless it involves a regular activity or they had some cause to remember it.
In the past you had a right not to self incriminate yourself (ie not to say anything). This unfortunatly does not apply in the U.K. Any more it's now "You have the right to remain silent, however if you do not say something that you later reley on in court...". Basicaly it can be used to make a jury think you invented it.
So now comes the interesting bit, contry to what most people belive since RIPA and 9/11 & 7/7 the authorities have little if no difficulty in getting access to these audit trails (just asking in the right way in a lot of cases).
And in some cases such as logs of transportation usage there is noproblem at all they can get a list of people who could have been in the area.
Now if you are a criminal you are probably aware of this so can take the appropriate steps to ensure you have a story backed up by several audit trails...
But as an inoccent person you would have no need to do such things. The Police however can put preasure on you saying "we have a witness who can put you at the scene and saw you using your phone" etc. If you are not wise to this then with your natural uncertainty and a few other prompts from the police you may well become very scared. Now if you are a vulnerable person you may end up saying things just to try and get yourself out of it, and so you start on a long slippery slope that makes you look guilty.
The only way out of it is to keep asking for representation before you will alow yourself to be interviewed. And make sure you actually get somebody you know, and say as little as possible even then untill you have had time to use the audit trails so you know atleast the what where and when yourself.
Oh and if you think it's a little fancifull, the "criminal hoodies" have already started swaping travel cards and mobile phones to cover each other.
Oh and the other way might have been to keep an electronic diary or some such with maybe some encryption, but guess what under RIPA you do not have the right to withold this. It is now questionable if "Priveledged information" (as described in PACE84 section 14) even applies any longer...