Like this one a lot - a really underrated gem of a film that's crying out for a decent DVD release.
If this were to be released on Blu I'd snap it up in an instant, although the prints I've seen haven't looked too fantastic, which could be a problem when constructing a decent HD master.
The script is pretty silly, but
TOE delivers some chills, plus some good gory set-pieces. It's also got a surprising amount of nudity for a Brit film of its time.
Here's the trailer to inspire the uniniatiated to check out this 1972 British classic: