I definitely agree with you on the proposals for making companies and government agencies/departments, (including NHS departments), identify themselves when they call you @thunderdragon
That is something that I have long thought makes a lot of sense and the fact that so many don't used to be incredibly frustrating to me until I decided to adopt a "**bleep** you!", attitude to people wanting to contact me without a valid caller ID.
I always advise companies who ask for my number that they'll only ever be able to use it for identification unless they show their main number, (or the number they expect me to call to contact them), as their caller ID.
Likewise because of my mail filtering I always advise them that they must include my name in their emails to me, otherwise I'll never see them.
It's my little way of trying to push the change we'd all probably like to see.
On the question of your number being divulged and receiving unwelcome calls I think that the current way is good enough.
The method is to report to the mobile company, report to the police and get a crime reference number, get a free number change whilst the calls become a criminal matter and the police take appropriate action, (hopefully).
I know it's a hassle changing number so it's not ideal, but by the same token, do not disturb on handsets and inclusive blocking can stop these types of calls being a hassle to ones daily life without the hassle of changing numbers.
Definitely with you on insisting non-private bodies and individuals should be made to display a valid caller ID, (I do think it should be numerical though, not alphanumeric, purely because alphanumeric is more difficult to block locally thanks to phones typical software).