Gonz ("Gonz" ) gurgled happily, sounding much like they were saying:
Because that's a fundamental principle of all UK law. It doesn't say anywhere in law that you can read a newspaper in the morning if you like, but you don't have to. By your assertion, that means you mustn't, because it doesn't say you must.
...except when there's no need to - in which case you can if you like.