Some MPs are like newspapers. You have this vague impression that things they say might actually have some research behind them, but end up screaming “No! It doesn’t work like that!” when they talk about a topic you know about.

It seems the Conservative MP Claire Perry (who surprisingly does have a Twitter account, which I didn’t expect to find) has fallen into this trap today, with her calls to create some sort of magic “opt-in” system for pornography. Here’s what she said:

Ms Perry, who represents Devizes, in Wiltshire, said: “As a mother with three children I know how difficult it is to keep children from seeing inappropriate material on the internet.

It’s not that hard. For younger children, try putting the computer somewhere public, such as the lounge or dining room – this is what I do with my kids. For older kids, if they have a computer in their room then it’s a trust thing and there are programs out there that will filter, if you’re worried. (Although they’re relatively easy to bypass with even a small amount of technical knowledge) Besides, do you really think they don’t have a copy of Playboy doing the rounds at school that someone’s older brother purchased?

“We already successfully regulate British TV channels, cinema screens, high street hoardings and newsagent shelves to stop children seeing inappropriate images and mobile phone companies are able to restrict access to adult material so why should the internet be any different?”

The key here is “British TV”. It’s broadcast in this country. The internet is more akin to everyone having a really big satellite dish in their back garden as one used to see many years ago and picking up TV stations from Scandinavia, just a really big dish that can get Australian TV too.

As she notes, mobile networks just about manage this except for the problem that a lot of sites that shouldn’t be are accidentally tagged: Most LGBT support sites are inaccessible for example. I could not, myself, support any system that cut people off from online avenues of support. It is likely that an opt-in system would cause issues for vulnerable adults too, where the internet account might be controlled by someone else who would become suspicious if they ask for the restriction to be removed.

Scaling such a solution to the kind of bandwidth levels we see on broadband could also be problematic, as we’ve already seen with failures in the Cleenfeed system – a system which isn’t perfect anyway, as it is incapable of filtering encrypted (HTTPS) sites. The more blocked sites you add to the system, the higher the load, the higher the cost (Thus the higher your broadband bill) and the greater the chance of it going wrong.

And finally it works better on mobiles because they generally don’t have the processing power to run proxy software to bypass ISP-based filters. You might give parents a safety net, but it’s a false one that’s easy for a teenager to bypass – as with any filters you put on the PC itself. It comes back to educating your kids and having some degree of trust that they’re not getting up to no good or, if you can’t trust them, putting the computer somewhere public.

Ms Perry added: “British internet service providers should share the responsibility to keep our children safe so I am calling for ISPs to offer an ‘opt-in’ system that uses age verification to access pornographic material.”

I have no idea how she intends to verify someone’s age online. Magic internet pixie dust, I suspect.

Yes, technology can seem like magic sometimes. But we’re not that good!