Those Cheryl Cole pictures
Nobody broke any law, by-law or pettifogging rules when Cheryl Cole's picture was taken. There is a properly accredited news and picture agency operating at Heathrow and their reporters and photographers are free to work within the boundaries laid down by BAA - namely that (a) security is not compromised; (b) specialist staff (police, immigration, customs etc) are not identified in close-up pictures or by name and (c) passengers who can be identified in a shot must give their permission.
Cheryl Cole had agreed to be photographed, and in fact was escorted through security and into the departure gate by the journalists.
Apart from newspaper photographs, don't forget the camera crews operating with impunity in programmes like Airport and Airline
When they film confrontations between passengers and staff (as in the wearingly familiar Easyjet stand-offs), everyone involved is asked to sign a release form afterwards. Those who decline have their faces blurred.