Death Line (Raw Meat in US) has the grooviest musical score of any horror: http://www.youtube.com/watch?v=VNkDrFdFylY.

Blood on Satan's Claw is a bit dodgy a la Salo etc. containing as it does a savage scene of simulated child rape during which a young Michele 'Ooh, Betty' Dotrice gets very hot under the collar indeed. No doubt they were all of-age, as were the Salo & Wicker Man schoolgirls - Lesley Mackie included, though she didn't do the naked fire leaping (always looked like fleshings to me!)

Mention of Alien prompts to shout DISTRICT 9!!! Quite the most absorbing sci-fi horror I've seen in ages. But not English, and neither's Alien, although they did use my beloved Blyth Power Station in one of the sequels with the late great Brian Glover.

Anyone see Frozen (2005)? Stars Shirley 'Moaning Myrtle' Henderson and was filmed here in Fleetwood. Not the best film in the world I grant, but it has one of the creepiest ending twists that really turns the whole thing around into a thing of deeply disturbing horror.