This has come about as it was suggested in two high profile child abuse trials the persons concerned had such images on their computers and smart phones.
None of us wants images of child abuse to be freely circulating by it because we find it disturbing and mainly is a record of actual abuse (or taken in the context of) but already there appear to be some limits leading to a BBC technology expect predicting a "Dialogue of the deaf".
The first is an many politicians do not appear to be able distinguish between what an Internet Service Provider is - a provider of internet connection - and what a search engine is - a means of locating often using tags in posts specific data on the web - such as websites.
The significance is that a search engine merely lists what is out there and may have 'safe search' options excluding certain terms, however of itself it doesn't restrict access. An internet provider may apply, if ordered, a block to its users of sites such as Pirate Bay that host copyright material sites plus sites deemed illegal, or possibly harmful.
One problem with the latter category is deciding what in fact IS harmful and a few years back the following image was blocked from wikipedia and is not allowed on ebay although it is legal in the UK and several hundred thousand people own it.
See the problem?
The other thing is, if any blocks are applied are applied at the ISP end, it is quite easy to install a 'Proxy' to tell it you aren't in the UK (and NOT on your isp) defeating it. One level above this would be to install the US navy browser TOR that effectively uses encryption bouncing internet traffic through relays hiding your location and what you're looking at.
This is available for Windows.
At the supply end there are many encryption packages for text and images used often in countries where internet censorship is common place yet information and pictures need to be gotten out. There's no reason to suppose those who spread such images aren't already using such techniques (it usually only the most naive who don't).
I seriously doubt anything of great significance will be achieved today although automatic tagging on images may assist removal from the most accessible sites by aiding identification of duplicates and that I'd welcome.
When it comes to 'adult porn' I really think the .xxx mandated approach would work if you had to set your browser to accept that domain so you could lock them off children's smartphones or laptops.
I also feel the only really safe option is for parents to use safety settings on browsers setting limits to suit their children's age and to talk about keeping safe online. It's your responsibility.