The Mark of Satan
The upstairs of Maidenhead library may have been used for the library scene. Thanks to Jill Finlay who suggested this was the location back in 2006. I haven’t visited the library to make 100% sure the location is correct but the exterior red metal roof structure would seem to confirm it is the right place.
Update March 2019 – Kevin Flanagan thinks that the library may actualy be in Hillingdon, as there is a very similar roofed library there and all the filming took place in and around Hillingdon. He says that there is also a similar library in Hayes. So the jurys out on this one !