From David Mery's accounts in The Gaurdian:

7.10 pm: From my workplace in Southwark, south London, I arrange by text message to meet my girlfriend (...)

7.21 pm: I enter Southwark tube station, passing uniformed police by the entrance, and more police beyond the gate. (...)

· they found my behaviour suspicious from direct observation and then from watching me on the CCTV system;
· I went into the station without looking at the police officers at the entrance or by the gates;
· two other men entered the station at about the same time as me;
· I am wearing a jacket "too warm for the season";
· I am carrying a bulky rucksack, and kept my rucksack with me at all times;
· I looked at people coming on the platform;
· I played with my phone and then took a paper from inside my jacket.

8.53pm: Arrested for suspicious behaviour and public nuisance, (...)

10:06pm: I am allowed a call to my girlfriend. She is crying (...)

10:30pm: I am put into an individual police cell. (...)

12:25-1:26 am: Three uniformed police officers search my flat and interview my girlfriend. (...)

On August 31 I arrive at the police station at 9 am as required by bail, with my solicitor. A plainclothes police officer tells us they are dropping the charges, and briefly apologises.

So even though the police consider me innocent there will remain some mention (what exactly?) in the PNC and, if they fully share their information with Interpol, in other police databases around the world as well. Isn't a state that keeps files on innocent persons a police state?