Is there a place where I can see what are the legal boundaries in the UK? Can a policeman detain me and make me miss my flight if I refuse to give my details at the airport? I don't like these growing restrictions.
For sure the police can cause you to miss your flight. The media often report cases where people missed flights due to questioning by the police.
I don't know the full details of the situation in the UK, but it's roughly like this: The police can stop you at any time if they "reasonably suspect" that you are carrying a weapon, or are in possession of a controlled substance. If they want to stop you without
"reasonable suspicion", they can do so under the Terrorism Act.
According to the following link, between 2000 and 2008 the UK police stopped and searched 108,714 people under the Terrorism Act. Of those, the number who were subsequently convicted of a terrorism offence was ... zero.
"Student Human Rights Network - Stop and search under the Terrorism Act 2000http://www.justice.org.uk/jshrn/newyear2010.htm#briefingsstop