I am an American who never heard of this before. I found out about it via a Horror Facebook group. I tried in vain to locate it, and finally Shudder has it. Holy crap! This scared the hell out of me! I have seen this several times and every time, it scares me. I've ordered the dvd hoping that it is, as the seller claims, region free, if not, I'll be selling it on Ebay.
The BBC really should release it on bluray for everyone. They'd make a fortune!