Depending on the way you interpret the proposed new legislation (and promised wave of crackdowns) on “violent pornography” stuff like this is potentially illegal again (read BME’s old Spannerman coverage) in the UK (both possesion and production). I don’t think* that there is any intent to go after consensual and non-commercial private activities such as those documented here, but if you’re a reader of commercial sites (as in sites where the models are paid to be tortured, rather than choosing it for themselves and sharing pictures), I would strongly urge you to keep the webcache on your computer cleared on the million to one chance they decide to go Big Brother on you.
I’d also encourage UK readers to visit the Spanner Trust.
* I may be overly optimistic here, given the lessons of history.