Not only the police knows you have landed from London when you go through passport control at Oslo Airport. You become data in a giant European surveillance system meant to prevent terror and stop illegal immigration. Nobody knows if it works.
In Norway this research was published by Aftenposten, Aftenbladet, Adresseavisen, Bergens Tidende, Faedrelandsvennen. Read more in Norwegian via http://www.aftenbladet.no/magasin/Grenselos-kontroll-535102b.html (paid content)