The ITV series Armchair Thriller was made in 1978 and 1980. Several of the stories were then broadcast in America as part of Mystery! on PBS.
I was probably a little too young when first looking at some of those episodes. The famous “Black Nun” sequence gave me horrible nightmares for months.
In some ways Dying Day remains my ideal kind of entertainment. It’s minimal and mysterious, enhanced only with atmospheric acoustic music and barely any special effects. The implausible puzzle story is compelling because the acting is superb and director Robert Tronson creates compositions that are just barely off-center.
I have a sentimental attachment to Dying Day, so perhaps it isn’t as good as I think. But if you love English thrillers, it has my highest recommendation.