@Fibbles and @nigel
@Fibbles:
I know where you are coming from; but they do base (almost) every soft decision they make on numbers. This filtering is not life and death ... If it was Dave would have already legislated. So he will look at the numbers - he already is, or he would have legislated - before he has to go hang himself out on a limb.
And, the closer an election is, the more they look at numbers.
What must be remembered, about all such similar campaigns, is that they never start with a big stick. They start by trying to persuade (phase 1) and then step up the pressure (using 3rd parties, instead of going out on a limb themselves) to get more of the job done (phase 2). Before finally - if necessary - legislating in Phase 3.
Seat Belts in Cars and the Smoking Ban. Both started, long before they were enacted, with a drip-drip-drip "nannying" persuassion campaign (all those Stop Smoking Ads you saw, over the years and years and years). That is usually followed by pressure being applied to involved third parties to assist with the campaign (Car makers fitting seat belts in the rear passenger seats). And then, when the country is softened up and a good number are already complying, the legislation is introduced.
So, the trick to stopping such a campaign is to get at it before it goes from stage-2 - where this is currently at, pressuring the big ISPs to offer suitable systems - to stage 3. Once enacted, getting rid of legislation is very difficult, especially after a change of government (unless the former opposition could have been persuaded to use it as a "vote winner").
And - as you wrote, Fibbles - in this instance, I doubt that would happen (too sensitive for a political campaign).
Do you agree that keeping children safe from harm is a good idea? <--- Never forget, almost no public-facing entity is going to publically disagree with that statement.
And @ Nigel:
A "public list" to demonstrate to .gov who has opted-out ... I understand what you are driving at (any mass opt-out may not be publicised, and so not as effective as it could be). The issue is, I think, that the peer-pressure to be on such a public list might be the straw that stopped some people opting-out.
The "invite to go on the list", would need to be carefully worded, so the above didn't happen.
And there would also be the issue of the "list" getting rubbished by opponents. I can see no way of "proving" everyone on it did actually opt-out. It may bring as much trouble as it brings good.
I do hate the "twee tag", but really - to be successful - this is Tea Party stuff. This is banging on every door in your street, explaining the Opt-Out Campaign and offering to assist with setting up a "better" filtering system (especially those neighbours with children ... especially them).
And in no way do I intend that to sound as easy as it was to type. In no way at all.
But if you want to beat this, it must be beaten quickly, comprehensively and in a way that can be shown to still be thinking of the children.