It still remains for the prosecution to prove that you are in possession of extreme pornographic images first. But if the prosecution can do this, then you are committing an offence: possession of these images is a crime per se in the same way that unlawful possession of drugs is. However, if you are found to be in such a position, the law lays down four reasons which exonerate you.

It's not as easy as you might think to prove possession of images on a computer. For example, if several people use the same machine, and you don't all have seperate passwords, which one of those people is "in possession"? All of them? Or the person who downloaded them? And how does the CPS prove who that was?

The law will not allow prosecutions based solely on the say-so of a police constable, and if there are not yet standards by which to measure whether an image satisfies the definition of "extreme pornography", it won't be long before there are. And it willl be some kind of reasonableness test.

The prosecution must establish that you are in possession of the images "beyond reasonable doubt". The existence of the photographs on your own personal computer is probably sufficient to do that in the same way that possession of car keys is probably sufficient if you are charged with being drunk in charge of a motor vehicle. If you cannot avail yourself of the prescribed defences, then you will be guilty.

But to use one of the prescribed defences, you only have to show "on the balance of probabilities" that it applies in your case. If you are not the exclusive user, then it becomes easier for you to show you did not know of their existence.

I don't see this as an attack on people with "kinks", or even people who go in for body modification. This does not, so far as I can see, outlaw pictures of Prince Albert piercings or of someone sitting on a butt plug with pegs attached to her nipples. It's an attack on conduct which goes beyond that, to a form of perversion/deviancy which is (a) extreme in nature and (b) of four specific types, namely, possession for sexual gratification of images which purport to show killings, genital mutilation, sex with a corpse or with an animal.

Our lawmakers perceive that such conduct is reprehensible, and I have strong doubts that there will be any groundswell of opinion against the new laws. I also think your concerns are misplaced, unless you do have images portraying those activities, which I doubt could be regarded as "educational" in any circumstances except, perhaps, for training sessions to show the police what to look for in their raids.