FIRES IN THE FALL (Christmas Special 1986)
This gave me nightmares, aged 11. Watched it last night for the first time since, and it still packs a punch.
A black-robed ghost warning of death, and sudden fires starting. Terrifying.
There are a couple of really sinister sequences, and it's well worth hunting out again. A couple of images are lodged in my mind from all those years ago, and I can recommend tracking down the DVD in order to see it again.
Bring back the days of scary Christmas telly!